diff --git a/src/Assert/CustomAssertionTrait.php b/src/Assert/CustomAssertionTrait.php
index c450fa583..8d61a4b65 100644
--- a/src/Assert/CustomAssertionTrait.php
+++ b/src/Assert/CustomAssertionTrait.php
@@ -63,8 +63,6 @@ private static function validURI(string $value, string $message = ''): void
         }
 
         try {
-            BaseAssert::notWhitespaceOnly($value, $message ?: '%s is not a SAML2-compliant URI');
-
             // If it doesn't have a scheme, it's not an absolute URI
             BaseAssert::regex($value, self::$scheme_regex, $message ?: '%s is not a SAML2-compliant URI');
         } catch (AssertionFailedException $e) {
@@ -82,6 +80,7 @@ private static function validEntityID(string $value, string $message = ''): void
         static::validURI($value);
 
         try {
+            BaseAssert::notWhitespaceOnly($value);
             BaseAssert::maxLength(
                 $value,
                 C::ENTITYID_MAX_LENGTH,
diff --git a/src/XML/StringElementTrait.php b/src/XML/StringElementTrait.php
new file mode 100644
index 000000000..c2d6fcb0d
--- /dev/null
+++ b/src/XML/StringElementTrait.php
@@ -0,0 +1,39 @@
+<?php
+
+declare(strict_types=1);
+
+namespace SimpleSAML\SAML2\XML;
+
+use SimpleSAML\Assert\Assert;
+use SimpleSAML\SAML2\Exception\ProtocolViolationException;
+use SimpleSAML\XML\StringElementTrait as BaseStringElementTrait;
+
+/**
+ * Trait extending the default StringElementTrait to comply with the restrictions added by the SAML 2.0 specifications.
+ *
+ * @package simplesamlphp/saml2
+ */
+trait StringElementTrait
+{
+    use BaseStringElementTrait;
+
+    /**
+     * Validate the content of the element.
+     *
+     * @param string $content  The value to go in the XML textContent
+     * @throws \Exception on failure
+     * @return void
+     */
+    protected function validateContent(/** @scrutinizer ignore-unused */ string $content): void
+    {
+        /**
+         * 1.3.1 String Values
+         *
+         * All SAML string values have the type xs:string, which is built in to the W3C XML Schema Datatypes
+         * specification [Schema2]. Unless otherwise noted in this specification or particular profiles, all strings in
+         * SAML messages MUST consist of at least one non-whitespace character (whitespace is defined in the
+         * XML Recommendation [XML] Section 2.3).
+         */
+        Assert::notWhitespaceOnly($content, ProtocolViolationException::class);
+    }
+}
diff --git a/src/XML/URIElementTrait.php b/src/XML/URIElementTrait.php
new file mode 100644
index 000000000..71d0ecbe4
--- /dev/null
+++ b/src/XML/URIElementTrait.php
@@ -0,0 +1,41 @@
+<?php
+
+declare(strict_types=1);
+
+namespace SimpleSAML\SAML2\XML;
+
+use SimpleSAML\Assert\Assert;
+use SimpleSAML\SAML2\Assert\Assert as SAMLAssert;
+use SimpleSAML\SAML2\Exception\ProtocolViolationException;
+use SimpleSAML\XML\Exception\SchemaViolationException;
+use SimpleSAML\XML\URIElementTrait as BaseURIElementTrait;
+
+/**
+ * Trait extending the default URIElementTrait to comply with the restrictions added by the SAML 2.0 specifications.
+ *
+ * @package simplesamlphp/saml2
+ */
+trait URIElementTrait
+{
+    use BaseURIElementTrait;
+
+    /**
+     * Validate the content of the element.
+     *
+     * @param string $content  The value to go in the XML textContent
+     * @throws \Exception on failure
+     * @return void
+     */
+    protected function validateContent(string $content): void
+    {
+        /**
+         * 1.3.2 URI Values
+         *
+         * Unless otherwise indicated in this specification, all URI reference values used within SAML-defined
+         * elements or attributes MUST consist of at least one non-whitespace character, and are REQUIRED to be
+         * absolute [RFC 2396].
+         */
+        Assert::notWhitespaceOnly($content, ProtocolViolationException::class);
+        SAMLAssert::validURI($content, SchemaViolationException::class);
+    }
+}
diff --git a/src/XML/ecp/RelayState.php b/src/XML/ecp/RelayState.php
index 4ef1f8658..c694e9992 100644
--- a/src/XML/ecp/RelayState.php
+++ b/src/XML/ecp/RelayState.php
@@ -7,12 +7,12 @@
 use DOMElement;
 use SimpleSAML\Assert\Assert;
 use SimpleSAML\SAML2\Exception\ProtocolViolationException;
+use SimpleSAML\SAML2\XML\StringElementTrait;
 use SimpleSAML\SOAP\Constants as C;
 use SimpleSAML\XML\Exception\InvalidDOMElementException;
 use SimpleSAML\XML\Exception\MissingAttributeException;
 use SimpleSAML\XML\SchemaValidatableElementInterface;
 use SimpleSAML\XML\SchemaValidatableElementTrait;
-use SimpleSAML\XML\StringElementTrait;
 
 /**
  * Class representing the ECP RelayState element.
diff --git a/src/XML/emd/RepublishTarget.php b/src/XML/emd/RepublishTarget.php
index 7dba25741..fb40885c2 100644
--- a/src/XML/emd/RepublishTarget.php
+++ b/src/XML/emd/RepublishTarget.php
@@ -5,8 +5,7 @@
 namespace SimpleSAML\SAML2\XML\emd;
 
 use SimpleSAML\Assert\Assert;
-use SimpleSAML\SAML2\Assert\Assert as SAMLAssert;
-use SimpleSAML\XML\StringElementTrait;
+use SimpleSAML\SAML2\XML\URIElementTrait;
 
 /**
  * Class implementing RepublishTarget.
@@ -15,7 +14,9 @@
  */
 final class RepublishTarget extends AbstractEmdElement
 {
-    use StringElementTrait;
+    use URIElementTrait {
+        URIElementTrait::validateContent as baseValidateContent;
+    }
 
 
     /**
@@ -36,7 +37,7 @@ public function __construct(string $content)
      */
     protected function validateContent(string $content): void
     {
-        SAMLAssert::validURI($content);
+        $this->baseValidateContent($content);
         Assert::same($content, 'http://edugain.org/');
     }
 }
diff --git a/src/XML/md/AbstractLocalizedName.php b/src/XML/md/AbstractLocalizedName.php
index 273e5051f..91cad4395 100644
--- a/src/XML/md/AbstractLocalizedName.php
+++ b/src/XML/md/AbstractLocalizedName.php
@@ -7,11 +7,12 @@
 use DOMElement;
 use SimpleSAML\Assert\Assert;
 use SimpleSAML\SAML2\Exception\ArrayValidationException;
+use SimpleSAML\SAML2\Exception\ProtocolViolationException;
+use SimpleSAML\SAML2\XML\StringElementTrait;
 use SimpleSAML\XML\ArrayizableElementInterface;
 use SimpleSAML\XML\Constants as C;
 use SimpleSAML\XML\Exception\InvalidDOMElementException;
 use SimpleSAML\XML\Exception\MissingAttributeException;
-use SimpleSAML\XML\StringElementTrait;
 
 use function array_key_first;
 
@@ -35,25 +36,12 @@ final public function __construct(
         protected string $language,
         string $value,
     ) {
-        Assert::notEmpty($language, 'xml:lang cannot be empty.');
+        Assert::notWhitespaceOnly($language, ProtocolViolationException::class);
 
         $this->setContent($value);
     }
 
 
-    /**
-     * Validate the content of the element.
-     *
-     * @param string $content  The value to go in the XML textContent
-     * @throws \Exception on failure
-     * @return void
-     */
-    protected function validateContent(string $content): void
-    {
-        Assert::notEmpty($content);
-    }
-
-
     /**
      * Get the language this string is localized in.
      *
diff --git a/src/XML/md/AdditionalMetadataLocation.php b/src/XML/md/AdditionalMetadataLocation.php
index bc52ea67b..5753c8d3d 100644
--- a/src/XML/md/AdditionalMetadataLocation.php
+++ b/src/XML/md/AdditionalMetadataLocation.php
@@ -7,11 +7,11 @@
 use DOMElement;
 use SimpleSAML\Assert\Assert;
 use SimpleSAML\SAML2\Assert\Assert as SAMLAssert;
+use SimpleSAML\SAML2\XML\URIElementTrait;
 use SimpleSAML\XML\Exception\InvalidDOMElementException;
 use SimpleSAML\XML\Exception\SchemaViolationException;
 use SimpleSAML\XML\SchemaValidatableElementInterface;
 use SimpleSAML\XML\SchemaValidatableElementTrait;
-use SimpleSAML\XML\StringElementTrait;
 
 use function trim;
 
@@ -23,7 +23,7 @@
 final class AdditionalMetadataLocation extends AbstractMdElement implements SchemaValidatableElementInterface
 {
     use SchemaValidatableElementTrait;
-    use StringElementTrait;
+    use URIElementTrait;
 
 
     /**
@@ -52,19 +52,6 @@ public function getNamespace(): string
     }
 
 
-    /**
-     * Validate the content of the element.
-     *
-     * @param string $content  The value to go in the XML textContent
-     * @throws \Exception on failure
-     * @return void
-     */
-    protected function validateContent(string $content): void
-    {
-        SAMLAssert::validURI($content, SchemaViolationException::class); // Covers the empty string
-    }
-
-
     /**
      * Initialize an AdditionalMetadataLocation element.
      *
diff --git a/src/XML/md/AffiliateMember.php b/src/XML/md/AffiliateMember.php
index 0b99a6424..b1d1f8485 100644
--- a/src/XML/md/AffiliateMember.php
+++ b/src/XML/md/AffiliateMember.php
@@ -5,9 +5,9 @@
 namespace SimpleSAML\SAML2\XML\md;
 
 use SimpleSAML\SAML2\Assert\Assert as SAMLAssert;
+use SimpleSAML\SAML2\XML\StringElementTrait;
 use SimpleSAML\XML\SchemaValidatableElementInterface;
 use SimpleSAML\XML\SchemaValidatableElementTrait;
-use SimpleSAML\XML\StringElementTrait;
 
 /**
  * Class implementing AffiliateMember.
diff --git a/src/XML/md/AttributeProfile.php b/src/XML/md/AttributeProfile.php
index fa02662ee..f80dcf339 100644
--- a/src/XML/md/AttributeProfile.php
+++ b/src/XML/md/AttributeProfile.php
@@ -7,10 +7,10 @@
 use DOMElement;
 use SimpleSAML\Assert\Assert;
 use SimpleSAML\SAML2\Assert\Assert as SAMLAssert;
+use SimpleSAML\SAML2\XML\StringElementTrait;
 use SimpleSAML\XML\Exception\InvalidDOMElementException;
 use SimpleSAML\XML\SchemaValidatableElementInterface;
 use SimpleSAML\XML\SchemaValidatableElementTrait;
-use SimpleSAML\XML\StringElementTrait;
 
 /**
  * Class implementing AttributeProfile.
@@ -30,35 +30,4 @@ public function __construct(string $content)
     {
         $this->setContent($content);
     }
-
-
-    /**
-     * Validate the content of the element.
-     *
-     * @param string $content  The value to go in the XML textContent
-     * @throws \Exception on failure
-     * @return void
-     */
-    protected function validateContent(string $content): void
-    {
-        SAMLAssert::validURI($content);
-    }
-
-
-    /**
-     * Convert XML into a AttributeProfile
-     *
-     * @param \DOMElement $xml The XML element we should load
-     * @return static
-     *
-     * @throws \SimpleSAML\XML\Exception\InvalidDOMElementException
-     *   If the qualified name of the supplied element is wrong
-     */
-    public static function fromXML(DOMElement $xml): static
-    {
-        Assert::same($xml->localName, 'AttributeProfile', InvalidDOMElementException::class);
-        Assert::same($xml->namespaceURI, AttributeProfile::NS, InvalidDOMElementException::class);
-
-        return new static($xml->textContent);
-    }
 }
diff --git a/src/XML/md/Company.php b/src/XML/md/Company.php
index a456d3f46..378bc075f 100644
--- a/src/XML/md/Company.php
+++ b/src/XML/md/Company.php
@@ -5,9 +5,9 @@
 namespace SimpleSAML\SAML2\XML\md;
 
 use SimpleSAML\Assert\Assert;
+use SimpleSAML\SAML2\XML\StringElementTrait;
 use SimpleSAML\XML\SchemaValidatableElementInterface;
 use SimpleSAML\XML\SchemaValidatableElementTrait;
-use SimpleSAML\XML\StringElementTrait;
 
 /**
  * Class implementing Company.
@@ -27,17 +27,4 @@ public function __construct(string $content)
     {
         $this->setContent($content);
     }
-
-
-    /**
-     * Validate the content of the element.
-     *
-     * @param string $content  The value to go in the XML textContent
-     * @throws \Exception on failure
-     * @return void
-     */
-    protected function validateContent(string $content): void
-    {
-        Assert::notEmpty($content, 'Company cannot be empty');
-    }
 }
diff --git a/src/XML/md/EmailAddress.php b/src/XML/md/EmailAddress.php
index 460aa9b21..c342fa5e3 100644
--- a/src/XML/md/EmailAddress.php
+++ b/src/XML/md/EmailAddress.php
@@ -6,10 +6,10 @@
 
 use SimpleSAML\Assert\Assert;
 use SimpleSAML\SAML2\Exception\ArrayValidationException;
+use SimpleSAML\SAML2\XML\StringElementTrait;
 use SimpleSAML\XML\ArrayizableElementInterface;
 use SimpleSAML\XML\SchemaValidatableElementInterface;
 use SimpleSAML\XML\SchemaValidatableElementTrait;
-use SimpleSAML\XML\StringElementTrait;
 
 use function array_key_first;
 use function preg_filter;
@@ -26,7 +26,9 @@ final class EmailAddress extends AbstractMdElement implements
     SchemaValidatableElementInterface
 {
     use SchemaValidatableElementTrait;
-    use StringElementTrait;
+    use StringElementTrait {
+        StringElementTrait::validateContent as baseValidateContent;
+    }
 
 
     /**
@@ -47,7 +49,7 @@ public function __construct(string $content)
      */
     protected function validateContent(string $content): void
     {
-        Assert::notEmpty($content, 'EmailAddress cannot be empty');
+        $this->baseValidateContent($content);
         Assert::email($content);
     }
 
diff --git a/src/XML/md/GivenName.php b/src/XML/md/GivenName.php
index e6c7dd491..a8c523625 100644
--- a/src/XML/md/GivenName.php
+++ b/src/XML/md/GivenName.php
@@ -5,9 +5,9 @@
 namespace SimpleSAML\SAML2\XML\md;
 
 use SimpleSAML\Assert\Assert;
+use SimpleSAML\SAML2\XML\StringElementTrait;
 use SimpleSAML\XML\SchemaValidatableElementInterface;
 use SimpleSAML\XML\SchemaValidatableElementTrait;
-use SimpleSAML\XML\StringElementTrait;
 
 /**
  * Class implementing GivenName.
@@ -27,17 +27,4 @@ public function __construct(string $content)
     {
         $this->setContent($content);
     }
-
-
-    /**
-     * Validate the content of the element.
-     *
-     * @param string $content  The value to go in the XML textContent
-     * @throws \Exception on failure
-     * @return void
-     */
-    protected function validateContent(string $content): void
-    {
-        Assert::notEmpty($content, 'GivenName cannot be empty');
-    }
 }
diff --git a/src/XML/md/NameIDFormat.php b/src/XML/md/NameIDFormat.php
index b271864b6..b48b87ded 100644
--- a/src/XML/md/NameIDFormat.php
+++ b/src/XML/md/NameIDFormat.php
@@ -7,10 +7,10 @@
 use DOMElement;
 use SimpleSAML\Assert\Assert;
 use SimpleSAML\SAML2\Assert\Assert as SAMLAssert;
+use SimpleSAML\SAML2\XML\URIElementTrait;
 use SimpleSAML\XML\Exception\InvalidDOMElementException;
 use SimpleSAML\XML\SchemaValidatableElementInterface;
 use SimpleSAML\XML\SchemaValidatableElementTrait;
-use SimpleSAML\XML\StringElementTrait;
 
 use function trim;
 
@@ -22,7 +22,7 @@
 final class NameIDFormat extends AbstractMdElement implements SchemaValidatableElementInterface
 {
     use SchemaValidatableElementTrait;
-    use StringElementTrait;
+    use URIElementTrait;
 
 
     /**
@@ -32,35 +32,4 @@ public function __construct(string $content)
     {
         $this->setContent($content);
     }
-
-
-    /**
-     * Validate the content of the element.
-     *
-     * @param string $content  The value to go in the XML textContent
-     * @throws \Exception on failure
-     * @return void
-     */
-    protected function validateContent(string $content): void
-    {
-        SAMLAssert::validURI($content);
-    }
-
-
-    /**
-     * Convert XML into an NameIDFormat
-     *
-     * @param \DOMElement $xml The XML element we should load
-     * @return static
-     *
-     * @throws \SimpleSAML\XML\Exception\InvalidDOMElementException
-     *   If the qualified name of the supplied element is wrong
-     */
-    public static function fromXML(DOMElement $xml): static
-    {
-        Assert::same($xml->localName, 'NameIDFormat', InvalidDOMElementException::class);
-        Assert::same($xml->namespaceURI, NameIDFormat::NS, InvalidDOMElementException::class);
-
-        return new static(trim($xml->textContent));
-    }
 }
diff --git a/src/XML/md/SurName.php b/src/XML/md/SurName.php
index 4ce4a0325..ab2d34f4f 100644
--- a/src/XML/md/SurName.php
+++ b/src/XML/md/SurName.php
@@ -5,9 +5,9 @@
 namespace SimpleSAML\SAML2\XML\md;
 
 use SimpleSAML\Assert\Assert;
+use SimpleSAML\SAML2\XML\StringElementTrait;
 use SimpleSAML\XML\SchemaValidatableElementInterface;
 use SimpleSAML\XML\SchemaValidatableElementTrait;
-use SimpleSAML\XML\StringElementTrait;
 
 /**
  * Class implementing SurName.
@@ -27,17 +27,4 @@ public function __construct(string $content)
     {
         $this->setContent($content);
     }
-
-
-    /**
-     * Validate the content of the element.
-     *
-     * @param string $content  The value to go in the XML textContent
-     * @throws \Exception on failure
-     * @return void
-     */
-    protected function validateContent(string $content): void
-    {
-        Assert::notEmpty($content, 'SurName cannot be empty');
-    }
 }
diff --git a/src/XML/md/TelephoneNumber.php b/src/XML/md/TelephoneNumber.php
index e3e5c191e..2eca6e176 100644
--- a/src/XML/md/TelephoneNumber.php
+++ b/src/XML/md/TelephoneNumber.php
@@ -6,10 +6,10 @@
 
 use SimpleSAML\Assert\Assert;
 use SimpleSAML\SAML2\Exception\ArrayValidationException;
+use SimpleSAML\SAML2\XML\StringElementTrait;
 use SimpleSAML\XML\ArrayizableElementInterface;
 use SimpleSAML\XML\SchemaValidatableElementInterface;
 use SimpleSAML\XML\SchemaValidatableElementTrait;
-use SimpleSAML\XML\StringElementTrait;
 
 use function array_key_first;
 
@@ -35,19 +35,6 @@ public function __construct(string $content)
     }
 
 
-    /**
-     * Validate the content of the element.
-     *
-     * @param string $content  The value to go in the XML textContent
-     * @throws \Exception on failure
-     * @return void
-     */
-    protected function validateContent(string $content): void
-    {
-        Assert::notEmpty($content, 'TelephoneNumber cannot be empty');
-    }
-
-
     /**
      * Create a class from an array
      *
diff --git a/src/XML/mdui/DomainHint.php b/src/XML/mdui/DomainHint.php
index 7fca048b0..715f9f2cf 100644
--- a/src/XML/mdui/DomainHint.php
+++ b/src/XML/mdui/DomainHint.php
@@ -6,9 +6,10 @@
 
 use SimpleSAML\Assert\Assert;
 use SimpleSAML\SAML2\Exception\InvalidArgumentException;
+use SimpleSAML\SAML2\Exception\ProtocolViolationException;
+use SimpleSAML\SAML2\XML\StringElementTrait;
 use SimpleSAML\XML\SchemaValidatableElementInterface;
 use SimpleSAML\XML\SchemaValidatableElementTrait;
-use SimpleSAML\XML\StringElementTrait;
 
 use function filter_var;
 use function preg_replace;
@@ -59,7 +60,7 @@ protected function sanitizeContent(string $content): string
     protected function validateContent(string $content): void
     {
         $sanitizedContent = $this->sanitizeContent($content);
-        Assert::notEmpty($sanitizedContent, 'DomainHint cannot be empty');
+        Assert::notWhitespaceOnly($sanitizedContent, ProtocolViolationException::class);
 
         if (!filter_var($sanitizedContent, FILTER_VALIDATE_DOMAIN, FILTER_FLAG_HOSTNAME)) {
             throw new InvalidArgumentException(sprintf('DomainHint is not a valid hostname;  %s', $sanitizedContent));
diff --git a/src/XML/mdui/GeolocationHint.php b/src/XML/mdui/GeolocationHint.php
index d9b9f1de2..c72a5e05e 100644
--- a/src/XML/mdui/GeolocationHint.php
+++ b/src/XML/mdui/GeolocationHint.php
@@ -6,9 +6,10 @@
 
 use SimpleSAML\Assert\Assert;
 use SimpleSAML\SAML2\Assert\Assert as SAMLAssert;
+use SimpleSAML\SAML2\Exception\ProtocolViolationException;
+use SimpleSAML\SAML2\XML\StringElementTrait;
 use SimpleSAML\XML\SchemaValidatableElementInterface;
 use SimpleSAML\XML\SchemaValidatableElementTrait;
-use SimpleSAML\XML\StringElementTrait;
 
 /**
  * Class implementing GeolocationHint.
@@ -67,7 +68,7 @@ protected function sanitizeContent(string $content): string
      */
     protected function validateContent(string $content): void
     {
-        Assert::notEmpty($content, 'GeolocationHint cannot be empty');
+        Assert::notWhitespaceOnly($content, ProtocolViolationException::class);
         // Assert::regex(
         //     $content,
         //     '/^geo:([-+]?\d+(?:\.\d+)?),([-+]?\d+(?:\.\d+)?)(?:\?z=(\d{1,2}))?$/',
diff --git a/src/XML/mdui/IPHint.php b/src/XML/mdui/IPHint.php
index c5ee890c0..5db3184a9 100644
--- a/src/XML/mdui/IPHint.php
+++ b/src/XML/mdui/IPHint.php
@@ -5,9 +5,9 @@
 namespace SimpleSAML\SAML2\XML\mdui;
 
 use SimpleSAML\Assert\Assert;
+use SimpleSAML\SAML2\XML\StringElementTrait;
 use SimpleSAML\XML\SchemaValidatableElementInterface;
 use SimpleSAML\XML\SchemaValidatableElementTrait;
-use SimpleSAML\XML\StringElementTrait;
 
 /**
  * Class implementing IPHint.
@@ -27,17 +27,4 @@ public function __construct(string $content)
     {
         $this->setContent($content);
     }
-
-
-    /**
-     * Validate the content of the element.
-     *
-     * @param string $content  The value to go in the XML textContent
-     * @throws \Exception on failure
-     * @return void
-     */
-    protected function validateContent(string $content): void
-    {
-        Assert::notEmpty($content, 'IPHint cannot be empty');
-    }
 }
diff --git a/src/XML/mdui/Logo.php b/src/XML/mdui/Logo.php
index e8e577180..2c553d356 100644
--- a/src/XML/mdui/Logo.php
+++ b/src/XML/mdui/Logo.php
@@ -9,11 +9,12 @@
 use SimpleSAML\Assert\Assert;
 //use SimpleSAML\SAML2\Assert\Assert as SAMLAssert;
 use SimpleSAML\SAML2\Exception\ArrayValidationException;
+use SimpleSAML\SAML2\Exception\ProtocolViolationException;
+use SimpleSAML\SAML2\XML\StringElementTrait;
 use SimpleSAML\XML\ArrayizableElementInterface;
 use SimpleSAML\XML\Exception\InvalidDOMElementException;
 use SimpleSAML\XML\SchemaValidatableElementInterface;
 use SimpleSAML\XML\SchemaValidatableElementTrait;
-use SimpleSAML\XML\StringElementTrait;
 
 use function filter_var;
 use function strval;
@@ -62,7 +63,8 @@ public function __construct(
     protected function validateContent(string $content): void
     {
         // NOTE:  we override the validateContent from the trait to be able to be less restrictive
-        // SAMLAssert::validURI($content, SchemaViolationException::class); // Covers the empty string
+        // SAMLAssert::validURI($content, SchemaViolationException::class);
+        Assert::notWhitespaceOnly($content, ProtocolViolationException::class);
         if (!filter_var(trim($content), FILTER_VALIDATE_URL) && substr(trim($content), 0, 5) !== 'data:') {
             throw new InvalidArgumentException('mdui:Logo is not a valid URL.');
         }
diff --git a/src/XML/saml/Action.php b/src/XML/saml/Action.php
index 08f66e0d0..7621ad65a 100644
--- a/src/XML/saml/Action.php
+++ b/src/XML/saml/Action.php
@@ -7,8 +7,8 @@
 use DOMElement;
 use SimpleSAML\Assert\Assert;
 use SimpleSAML\SAML2\Assert\Assert as SAMLAssert;
+use SimpleSAML\SAML2\XML\StringElementTrait;
 use SimpleSAML\XML\Exception\InvalidDOMElementException;
-use SimpleSAML\XML\StringElementTrait;
 
 /**
  * Class representing SAML2 Action
diff --git a/src/XML/saml/AssertionIDRef.php b/src/XML/saml/AssertionIDRef.php
index 16abdb539..ab905d5b9 100644
--- a/src/XML/saml/AssertionIDRef.php
+++ b/src/XML/saml/AssertionIDRef.php
@@ -6,11 +6,11 @@
 
 use DOMElement;
 use SimpleSAML\Assert\Assert;
+use SimpleSAML\SAML2\XML\StringElementTrait;
 use SimpleSAML\XML\Exception\InvalidDOMElementException;
 use SimpleSAML\XML\Exception\SchemaViolationException;
 use SimpleSAML\XML\SchemaValidatableElementInterface;
 use SimpleSAML\XML\SchemaValidatableElementTrait;
-use SimpleSAML\XML\StringElementTrait;
 
 /**
  * Class representing a saml:AssertionIDRef element.
@@ -20,7 +20,9 @@
 final class AssertionIDRef extends AbstractSamlElement implements SchemaValidatableElementInterface
 {
     use SchemaValidatableElementTrait;
-    use StringElementTrait;
+    use StringElementTrait {
+        StringElementTrait::validateContent as baseValidateContent;
+    }
 
 
     /**
@@ -41,39 +43,7 @@ public function __construct(string $content)
      */
     protected function validateContent(string $content): void
     {
-        Assert::validNCName($content, SchemaViolationException::class); // Covers the empty string
-    }
-
-
-    /**
-     * Convert XML into an AssertionIDRef
-     *
-     * @param \DOMElement $xml The XML element we should load
-     * @return static
-     *
-     * @throws \SimpleSAML\XML\Exception\InvalidDOMElementException
-     *   If the qualified name of the supplied element is wrong
-     */
-    public static function fromXML(DOMElement $xml): static
-    {
-        Assert::same($xml->localName, 'AssertionIDRef', InvalidDOMElementException::class);
-        Assert::same($xml->namespaceURI, AssertionIDRef::NS, InvalidDOMElementException::class);
-
-        return new static($xml->textContent);
-    }
-
-
-    /**
-     * Convert this AssertionIDRef to XML.
-     *
-     * @param \DOMElement $parent The element we are converting to XML.
-     * @return \DOMElement The XML element after adding the data corresponding to this AssertionIDRef.
-     */
-    public function toXML(?DOMElement $parent = null): DOMElement
-    {
-        $element = $this->instantiateParentElement($parent);
-        $element->textContent = $this->getContent();
-
-        return $element;
+        $this->baseValidateContent($content);
+        Assert::validNCName($content, SchemaViolationException::class);
     }
 }
diff --git a/src/XML/saml/AssertionURIRef.php b/src/XML/saml/AssertionURIRef.php
index 364624580..16634123f 100644
--- a/src/XML/saml/AssertionURIRef.php
+++ b/src/XML/saml/AssertionURIRef.php
@@ -4,13 +4,9 @@
 
 namespace SimpleSAML\SAML2\XML\saml;
 
-use DOMElement;
-use SimpleSAML\Assert\Assert;
-use SimpleSAML\SAML2\Assert\Assert as SAMLAssert;
-use SimpleSAML\XML\Exception\InvalidDOMElementException;
+use SimpleSAML\SAML2\XML\URIElementTrait;
 use SimpleSAML\XML\SchemaValidatableElementInterface;
 use SimpleSAML\XML\SchemaValidatableElementTrait;
-use SimpleSAML\XML\StringElementTrait;
 
 /**
  * Class representing a saml:AssertionURIRef element.
@@ -20,7 +16,7 @@
 final class AssertionURIRef extends AbstractSamlElement implements SchemaValidatableElementInterface
 {
     use SchemaValidatableElementTrait;
-    use StringElementTrait;
+    use URIElementTrait;
 
 
     /**
@@ -30,50 +26,4 @@ public function __construct(string $content)
     {
         $this->setContent($content);
     }
-
-
-    /**
-     * Validate the content of the element.
-     *
-     * @param string $content  The value to go in the XML textContent
-     * @throws \Exception on failure
-     * @return void
-     */
-    protected function validateContent(string $content): void
-    {
-        SAMLAssert::validURI($content);
-    }
-
-
-    /**
-     * Convert XML into an AssertionURIRef
-     *
-     * @param \DOMElement $xml The XML element we should load
-     * @return static
-     *
-     * @throws \SimpleSAML\XML\Exception\InvalidDOMElementException
-     *   If the qualified name of the supplied element is wrong
-     */
-    public static function fromXML(DOMElement $xml): static
-    {
-        Assert::same($xml->localName, 'AssertionURIRef', InvalidDOMElementException::class);
-        Assert::same($xml->namespaceURI, AssertionURIRef::NS, InvalidDOMElementException::class);
-
-        return new static($xml->textContent);
-    }
-
-
-    /**
-     * Convert this AssertionURIRef to XML.
-     *
-     * @param \DOMElement $parent The element we are converting to XML.
-     * @return \DOMElement The XML element after adding the data corresponding to this Condition.
-     */
-    public function toXML(?DOMElement $parent = null): DOMElement
-    {
-        $element = $this->instantiateParentElement($parent);
-        $element->textContent = $this->getContent();
-
-        return $element;
-    }
 }
diff --git a/src/XML/saml/Audience.php b/src/XML/saml/Audience.php
index 914e55637..30b56494f 100644
--- a/src/XML/saml/Audience.php
+++ b/src/XML/saml/Audience.php
@@ -4,13 +4,10 @@
 
 namespace SimpleSAML\SAML2\XML\saml;
 
-use DOMElement;
-use SimpleSAML\Assert\Assert;
 use SimpleSAML\SAML2\Assert\Assert as SAMLAssert;
-use SimpleSAML\XML\Exception\InvalidDOMElementException;
+use SimpleSAML\SAML2\XML\URIElementTrait;
 use SimpleSAML\XML\SchemaValidatableElementInterface;
 use SimpleSAML\XML\SchemaValidatableElementTrait;
-use SimpleSAML\XML\StringElementTrait;
 
 /**
  * Class representing a saml:Audience element.
@@ -20,7 +17,7 @@
 final class Audience extends AbstractSamlElement implements SchemaValidatableElementInterface
 {
     use SchemaValidatableElementTrait;
-    use StringElementTrait;
+    use URIElementTrait;
 
 
     /**
@@ -43,37 +40,4 @@ protected function validateContent(string $content): void
     {
         SAMLAssert::validEntityID($content);
     }
-
-
-    /**
-     * Convert XML into an Audience
-     *
-     * @param \DOMElement $xml The XML element we should load
-     * @return static
-     *
-     * @throws \SimpleSAML\XML\Exception\InvalidDOMElementException
-     *   If the qualified name of the supplied element is wrong
-     */
-    public static function fromXML(DOMElement $xml): static
-    {
-        Assert::same($xml->localName, 'Audience', InvalidDOMElementException::class);
-        Assert::same($xml->namespaceURI, Audience::NS, InvalidDOMElementException::class);
-
-        return new static($xml->textContent);
-    }
-
-
-    /**
-     * Convert this Audience to XML.
-     *
-     * @param \DOMElement $parent The element we are converting to XML.
-     * @return \DOMElement The XML element after adding the data corresponding to this Audience.
-     */
-    public function toXML(?DOMElement $parent = null): DOMElement
-    {
-        $element = $this->instantiateParentElement($parent);
-        $element->textContent = $this->getContent();
-
-        return $element;
-    }
 }
diff --git a/src/XML/saml/AuthenticatingAuthority.php b/src/XML/saml/AuthenticatingAuthority.php
index f53f21e8d..2fabef427 100644
--- a/src/XML/saml/AuthenticatingAuthority.php
+++ b/src/XML/saml/AuthenticatingAuthority.php
@@ -4,13 +4,10 @@
 
 namespace SimpleSAML\SAML2\XML\saml;
 
-use DOMElement;
-use SimpleSAML\Assert\Assert;
 use SimpleSAML\SAML2\Assert\Assert as SAMLAssert;
-use SimpleSAML\XML\Exception\InvalidDOMElementException;
+use SimpleSAML\SAML2\XML\URIElementTrait;
 use SimpleSAML\XML\SchemaValidatableElementInterface;
 use SimpleSAML\XML\SchemaValidatableElementTrait;
-use SimpleSAML\XML\StringElementTrait;
 
 /**
  * Class representing a saml:AuthenticatingAuthority element.
@@ -20,7 +17,7 @@
 final class AuthenticatingAuthority extends AbstractSamlElement implements SchemaValidatableElementInterface
 {
     use SchemaValidatableElementTrait;
-    use StringElementTrait;
+    use URIElementTrait;
 
 
     /**
@@ -41,24 +38,6 @@ public function __construct(string $content)
      */
     protected function validateContent(string $content): void
     {
-        SAMLAssert::validURI($content);
-    }
-
-
-    /**
-     * Convert XML into an AuthenticatingAuthority
-     *
-     * @param \DOMElement $xml The XML element we should load
-     * @return static
-     *
-     * @throws \SimpleSAML\XML\Exception\InvalidDOMElementException
-     *   If the qualified name of the supplied element is wrong
-     */
-    public static function fromXML(DOMElement $xml): static
-    {
-        Assert::same($xml->localName, 'AuthenticatingAuthority', InvalidDOMElementException::class);
-        Assert::same($xml->namespaceURI, AuthenticatingAuthority::NS, InvalidDOMElementException::class);
-
-        return new static($xml->textContent);
+        SAMLAssert::validEntityID($content);
     }
 }
diff --git a/src/XML/saml/AuthnContextClassRef.php b/src/XML/saml/AuthnContextClassRef.php
index 3e012cfa1..45602812f 100644
--- a/src/XML/saml/AuthnContextClassRef.php
+++ b/src/XML/saml/AuthnContextClassRef.php
@@ -5,9 +5,9 @@
 namespace SimpleSAML\SAML2\XML\saml;
 
 use SimpleSAML\SAML2\Assert\Assert as SAMLAssert;
+use SimpleSAML\SAML2\XML\URIElementTrait;
 use SimpleSAML\XML\SchemaValidatableElementInterface;
 use SimpleSAML\XML\SchemaValidatableElementTrait;
-use SimpleSAML\XML\StringElementTrait;
 
 /**
  * Class representing SAML2 AuthnContextClassRef
@@ -17,7 +17,7 @@
 final class AuthnContextClassRef extends AbstractSamlElement implements SchemaValidatableElementInterface
 {
     use SchemaValidatableElementTrait;
-    use StringElementTrait;
+    use URIElementTrait;
 
 
     /**
@@ -27,17 +27,4 @@ public function __construct(string $content)
     {
         $this->setContent($content);
     }
-
-
-    /**
-     * Validate the content of the element.
-     *
-     * @param string $content  The value to go in the XML textContent
-     * @throws \Exception on failure
-     * @return void
-     */
-    protected function validateContent(string $content): void
-    {
-        SAMLAssert::validURI($content);
-    }
 }
diff --git a/src/XML/saml/AuthnContextDeclRef.php b/src/XML/saml/AuthnContextDeclRef.php
index 707b08710..f3e2e582e 100644
--- a/src/XML/saml/AuthnContextDeclRef.php
+++ b/src/XML/saml/AuthnContextDeclRef.php
@@ -5,9 +5,9 @@
 namespace SimpleSAML\SAML2\XML\saml;
 
 use SimpleSAML\SAML2\Assert\Assert as SAMLAssert;
+use SimpleSAML\SAML2\XML\URIElementTrait;
 use SimpleSAML\XML\SchemaValidatableElementInterface;
 use SimpleSAML\XML\SchemaValidatableElementTrait;
-use SimpleSAML\XML\StringElementTrait;
 
 /**
  * Class representing SAML2 AuthnContextDeclRef
@@ -17,7 +17,7 @@
 final class AuthnContextDeclRef extends AbstractSamlElement implements SchemaValidatableElementInterface
 {
     use SchemaValidatableElementTrait;
-    use StringElementTrait;
+    use URIElementTrait;
 
 
     /**
@@ -27,17 +27,4 @@ public function __construct(string $content)
     {
         $this->setContent($content);
     }
-
-
-    /**
-     * Validate the content of the element.
-     *
-     * @param string $content  The value to go in the XML textContent
-     * @throws \Exception on failure
-     * @return void
-     */
-    protected function validateContent(string $content): void
-    {
-        SAMLAssert::validURI($content);
-    }
 }
diff --git a/src/XML/saml/NameIDType.php b/src/XML/saml/NameIDType.php
index 46f224970..825b118d5 100644
--- a/src/XML/saml/NameIDType.php
+++ b/src/XML/saml/NameIDType.php
@@ -7,8 +7,8 @@
 use DOMElement;
 use SimpleSAML\Assert\Assert;
 use SimpleSAML\SAML2\Assert\Assert as SAMLAssert;
+use SimpleSAML\SAML2\XML\StringElementTrait;
 use SimpleSAML\XML\Exception\InvalidDOMElementException;
-use SimpleSAML\XML\StringElementTrait;
 
 /**
  * SAML NameIDType abstract data type.
diff --git a/src/XML/samlp/GetComplete.php b/src/XML/samlp/GetComplete.php
index affc3f535..4e7ea7514 100644
--- a/src/XML/samlp/GetComplete.php
+++ b/src/XML/samlp/GetComplete.php
@@ -4,14 +4,11 @@
 
 namespace SimpleSAML\SAML2\XML\samlp;
 
-use DOMElement;
 use SimpleSAML\Assert\Assert;
-use SimpleSAML\SAML2\Assert\Assert as SAMLAssert;
 use SimpleSAML\SAML2\Exception\ArrayValidationException;
-use SimpleSAML\XML\Exception\InvalidDOMElementException;
+use SimpleSAML\SAML2\XML\URIElementTrait;
 use SimpleSAML\XML\SchemaValidatableElementInterface;
 use SimpleSAML\XML\SchemaValidatableElementTrait;
-use SimpleSAML\XML\StringElementTrait;
 
 use function array_key_first;
 
@@ -23,7 +20,7 @@
 final class GetComplete extends AbstractSamlpElement implements SchemaValidatableElementInterface
 {
     use SchemaValidatableElementTrait;
-    use StringElementTrait;
+    use URIElementTrait;
 
 
     /**
@@ -35,37 +32,6 @@ public function __construct(string $content)
     }
 
 
-    /**
-     * Validate the content of the element.
-     *
-     * @param string $content  The value to go in the XML textContent
-     * @throws \Exception on failure
-     * @return void
-     */
-    protected function validateContent(string $content): void
-    {
-        SAMLAssert::validURI($content);
-    }
-
-
-    /**
-     * Convert XML into an GetComplete
-     *
-     * @param \DOMElement $xml The XML element we should load
-     * @return static
-     *
-     * @throws \SimpleSAML\XML\Exception\InvalidDOMElementException
-     *   If the qualified name of the supplied element is wrong
-     */
-    public static function fromXML(DOMElement $xml): static
-    {
-        Assert::same($xml->localName, 'GetComplete', InvalidDOMElementException::class);
-        Assert::same($xml->namespaceURI, GetComplete::NS, InvalidDOMElementException::class);
-
-        return new static($xml->textContent);
-    }
-
-
     /**
      * Create a class from an array
      *
diff --git a/src/XML/samlp/RequesterID.php b/src/XML/samlp/RequesterID.php
index 0808dd2ed..741037d8e 100644
--- a/src/XML/samlp/RequesterID.php
+++ b/src/XML/samlp/RequesterID.php
@@ -4,14 +4,11 @@
 
 namespace SimpleSAML\SAML2\XML\samlp;
 
-use DOMElement;
 use SimpleSAML\Assert\Assert;
-use SimpleSAML\SAML2\Assert\Assert as SAMLAssert;
 use SimpleSAML\SAML2\Exception\ArrayValidationException;
-use SimpleSAML\XML\Exception\InvalidDOMElementException;
+use SimpleSAML\SAML2\XML\URIElementTrait;
 use SimpleSAML\XML\SchemaValidatableElementInterface;
 use SimpleSAML\XML\SchemaValidatableElementTrait;
-use SimpleSAML\XML\StringElementTrait;
 
 use function array_key_first;
 
@@ -23,7 +20,7 @@
 final class RequesterID extends AbstractSamlpElement implements SchemaValidatableElementInterface
 {
     use SchemaValidatableElementTrait;
-    use StringElementTrait;
+    use URIElementTrait;
 
 
     /**
@@ -35,37 +32,6 @@ public function __construct(string $content)
     }
 
 
-    /**
-     * Validate the content of the element.
-     *
-     * @param string $content  The value to go in the XML textContent
-     * @throws \Exception on failure
-     * @return void
-     */
-    protected function validateContent(string $content): void
-    {
-        SAMLAssert::validEntityID($content);
-    }
-
-
-    /**
-     * Convert XML into an RequesterID
-     *
-     * @param \DOMElement $xml The XML element we should load
-     * @return static
-     *
-     * @throws \SimpleSAML\XML\Exception\InvalidDOMElementException
-     *   If the qualified name of the supplied element is wrong
-     */
-    public static function fromXML(DOMElement $xml): static
-    {
-        Assert::same($xml->localName, 'RequesterID', InvalidDOMElementException::class);
-        Assert::same($xml->namespaceURI, RequesterID::NS, InvalidDOMElementException::class);
-
-        return new static($xml->textContent);
-    }
-
-
     /**
      * Create a class from an array
      *
diff --git a/src/XML/samlp/SessionIndex.php b/src/XML/samlp/SessionIndex.php
index 2d58e589d..6d7bee65b 100644
--- a/src/XML/samlp/SessionIndex.php
+++ b/src/XML/samlp/SessionIndex.php
@@ -4,12 +4,9 @@
 
 namespace SimpleSAML\SAML2\XML\samlp;
 
-use DOMElement;
-use SimpleSAML\Assert\Assert;
-use SimpleSAML\XML\Exception\InvalidDOMElementException;
+use SimpleSAML\SAML2\XML\StringElementTrait;
 use SimpleSAML\XML\SchemaValidatableElementInterface;
 use SimpleSAML\XML\SchemaValidatableElementTrait;
-use SimpleSAML\XML\StringElementTrait;
 
 /**
  * Class representing a samlp:SessionIndex element.
@@ -29,35 +26,4 @@ public function __construct(string $content)
     {
         $this->setContent($content);
     }
-
-
-    /**
-     * Validate the content of the element.
-     *
-     * @param string $content  The value to go in the XML textContent
-     * @throws \Exception on failure
-     * @return void
-     */
-    protected function validateContent(string $content): void
-    {
-        Assert::notWhitespaceOnly($content);
-    }
-
-
-    /**
-     * Convert XML into an SessionIndex
-     *
-     * @param \DOMElement $xml The XML element we should load
-     * @return static
-     *
-     * @throws \SimpleSAML\XML\Exception\InvalidDOMElementException
-     *   If the qualified name of the supplied element is wrong
-     */
-    public static function fromXML(DOMElement $xml): static
-    {
-        Assert::same($xml->localName, 'SessionIndex', InvalidDOMElementException::class);
-        Assert::same($xml->namespaceURI, SessionIndex::NS, InvalidDOMElementException::class);
-
-        return new static($xml->textContent);
-    }
 }
diff --git a/src/XML/samlp/StatusMessage.php b/src/XML/samlp/StatusMessage.php
index 378db03a0..00ee4b4f9 100644
--- a/src/XML/samlp/StatusMessage.php
+++ b/src/XML/samlp/StatusMessage.php
@@ -4,12 +4,9 @@
 
 namespace SimpleSAML\SAML2\XML\samlp;
 
-use DOMElement;
-use SimpleSAML\Assert\Assert;
-use SimpleSAML\XML\Exception\InvalidDOMElementException;
+use SimpleSAML\SAML2\XML\StringElementTrait;
 use SimpleSAML\XML\SchemaValidatableElementInterface;
 use SimpleSAML\XML\SchemaValidatableElementTrait;
-use SimpleSAML\XML\StringElementTrait;
 
 /**
  * Class representing a samlp:StatusMessage element.
@@ -29,35 +26,4 @@ public function __construct(string $content)
     {
         $this->setContent($content);
     }
-
-
-    /**
-     * Validate the content of the element.
-     *
-     * @param string $content  The value to go in the XML textContent
-     * @throws \Exception on failure
-     * @return void
-     */
-    protected function validateContent(string $content): void
-    {
-        Assert::notWhitespaceOnly($content);
-    }
-
-
-    /**
-     * Convert XML into an StatusMessage
-     *
-     * @param \DOMElement $xml The XML element we should load
-     * @return static
-     *
-     * @throws \SimpleSAML\XML\Exception\InvalidDOMElementException
-     *   If the qualified name of the supplied element is wrong
-     */
-    public static function fromXML(DOMElement $xml): static
-    {
-        Assert::same($xml->localName, 'StatusMessage', InvalidDOMElementException::class);
-        Assert::same($xml->namespaceURI, StatusMessage::NS, InvalidDOMElementException::class);
-
-        return new static($xml->textContent);
-    }
 }
diff --git a/src/XML/shibmd/Scope.php b/src/XML/shibmd/Scope.php
index 6e087dbfa..1635d22da 100644
--- a/src/XML/shibmd/Scope.php
+++ b/src/XML/shibmd/Scope.php
@@ -6,10 +6,10 @@
 
 use DOMElement;
 use SimpleSAML\Assert\Assert;
+use SimpleSAML\SAML2\XML\StringElementTrait;
 use SimpleSAML\XML\Exception\InvalidDOMElementException;
 use SimpleSAML\XML\SchemaValidatableElementInterface;
 use SimpleSAML\XML\SchemaValidatableElementTrait;
-use SimpleSAML\XML\StringElementTrait;
 
 /**
  * Class which represents the Scope element found in Shibboleth metadata.
@@ -37,19 +37,6 @@ public function __construct(
     }
 
 
-    /**
-     * Validate the content of the element.
-     *
-     * @param string $content  The value to go in the XML textContent
-     * @throws \Exception on failure
-     * @return void
-     */
-    protected function validateContent(string $content): void
-    {
-        Assert::notWhitespaceOnly($content);
-    }
-
-
     /**
      * Collect the value of the regexp-property
      *
diff --git a/tests/SAML2/XML/md/AbstractLocalizedNameTest.php b/tests/SAML2/XML/md/AbstractLocalizedNameTest.php
index bd25ac7d6..f33c39bf5 100644
--- a/tests/SAML2/XML/md/AbstractLocalizedNameTest.php
+++ b/tests/SAML2/XML/md/AbstractLocalizedNameTest.php
@@ -10,10 +10,12 @@
 use PHPUnit\Framework\TestCase;
 use SimpleSAML\Assert\AssertionFailedException;
 use SimpleSAML\SAML2\Constants as C;
+use SimpleSAML\SAML2\Exception\ProtocolViolationException;
 use SimpleSAML\SAML2\XML\md\AbstractLocalizedName;
 use SimpleSAML\SAML2\XML\md\AbstractMdElement;
 use SimpleSAML\SAML2\XML\md\ServiceDescription;
 use SimpleSAML\XML\DOMDocumentFactory;
+use SimpleSAML\XML\Exception\MissingAttributeException;
 
 use function dirname;
 
@@ -50,8 +52,8 @@ public static function setUpBeforeClass(): void
      */
     public function testMarshallingWithEmptyLang(): void
     {
-        $this->expectException(AssertionFailedException::class);
-        $this->expectExceptionMessage('xml:lang cannot be empty.');
+        $this->expectException(ProtocolViolationException::class);
+        $this->expectExceptionMessage('Expected a non-whitespace string. Got: ""');
 
         new ServiceDescription('', 'Academic Journals R US and only us');
     }
@@ -62,8 +64,8 @@ public function testMarshallingWithEmptyLang(): void
      */
     public function testMarshallingWithEmptyValue(): void
     {
-        $this->expectException(AssertionFailedException::class);
-        $this->expectExceptionMessage('Expected a non-empty value. Got: ""');
+        $this->expectException(ProtocolViolationException::class);
+        $this->expectExceptionMessage('Expected a non-whitespace string. Got: ""');
 
         new ServiceDescription('en', '');
     }
@@ -80,7 +82,7 @@ public function testUnmarshallingWithoutLang(): void
         $xmlRepresentation = clone self::$xmlRepresentation;
         $xmlRepresentation->documentElement->removeAttributeNS(C::NS_XML, 'lang');
 
-        $this->expectException(AssertionFailedException::class);
+        $this->expectException(MissingAttributeException::class);
         $this->expectExceptionMessage('Missing xml:lang from ServiceDescription');
 
         ServiceDescription::fromXML($xmlRepresentation->documentElement);
@@ -95,8 +97,8 @@ public function testUnmarshallingWithEmptyLang(): void
         $xmlRepresentation = clone self::$xmlRepresentation;
         $xmlRepresentation->documentElement->setAttributeNS(C::NS_XML, 'lang', '');
 
-        $this->expectException(AssertionFailedException::class);
-        $this->expectExceptionMessage('xml:lang cannot be empty.');
+        $this->expectException(ProtocolViolationException::class);
+        $this->expectExceptionMessage('Expected a non-whitespace string. Got: ""');
 
         ServiceDescription::fromXML($xmlRepresentation->documentElement);
     }
@@ -110,8 +112,8 @@ public function testUnmarshallingWithEmptyValue(): void
         $xmlRepresentation = clone self::$xmlRepresentation;
         $xmlRepresentation->documentElement->textContent = '';
 
-        $this->expectException(AssertionFailedException::class);
-        $this->expectExceptionMessage('Expected a non-empty value. Got: ""');
+        $this->expectException(ProtocolViolationException::class);
+        $this->expectExceptionMessage('Expected a non-whitespace string. Got: ""');
 
         ServiceDescription::fromXML($xmlRepresentation->documentElement);
     }
diff --git a/tests/SAML2/XML/md/ServiceNameTest.php b/tests/SAML2/XML/md/ServiceNameTest.php
index 3c7d8543e..abd7928e7 100644
--- a/tests/SAML2/XML/md/ServiceNameTest.php
+++ b/tests/SAML2/XML/md/ServiceNameTest.php
@@ -9,6 +9,7 @@
 use PHPUnit\Framework\TestCase;
 use SimpleSAML\Assert\AssertionFailedException;
 use SimpleSAML\SAML2\Constants as C;
+use SimpleSAML\SAML2\Exception\ProtocolViolationException;
 use SimpleSAML\SAML2\XML\md\AbstractLocalizedName;
 use SimpleSAML\SAML2\XML\md\AbstractMdElement;
 use SimpleSAML\SAML2\XML\md\ServiceName;
@@ -72,8 +73,8 @@ public function testMarshalling(): void
      */
     public function testMarshallingWithEmptyLang(): void
     {
-        $this->expectException(AssertionFailedException::class);
-        $this->expectExceptionMessage('xml:lang cannot be empty.');
+        $this->expectException(ProtocolViolationException::class);
+        $this->expectExceptionMessage('Expected a non-whitespace string. Got: ""');
 
         new ServiceName('', 'Academic Journals R US');
     }
@@ -105,8 +106,8 @@ public function testUnmarshallingWithEmptyLang(): void
         $xmlRepresentation = clone self::$xmlRepresentation;
         $xmlRepresentation->documentElement->setAttributeNS(C::NS_XML, 'lang', '');
 
-        $this->expectException(AssertionFailedException::class);
-        $this->expectExceptionMessage('xml:lang cannot be empty.');
+        $this->expectException(ProtocolViolationException::class);
+        $this->expectExceptionMessage('Expected a non-whitespace string. Got: ""');
 
         ServiceName::fromXML($xmlRepresentation->documentElement);
     }