From 3fd63041aad35d831458019565b2791ddd550d73 Mon Sep 17 00:00:00 2001
From: Tim Pillinger <26465611+wxtim@users.noreply.github.com>
Date: Wed, 27 Oct 2021 12:15:33 +0100
Subject: [PATCH] changed error message in response to review.

---
 cylc/rose/platform_utils.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/cylc/rose/platform_utils.py b/cylc/rose/platform_utils.py
index 1994b535..eef57631 100644
--- a/cylc/rose/platform_utils.py
+++ b/cylc/rose/platform_utils.py
@@ -50,8 +50,8 @@ def get_platform_from_task_def(
     platform = get_platform(task_spec)
     if platform is None:
         raise PlatformLookupError(
-            'Platform lookup failed because the platform definition for'
-            f' task {task} is {task_spec["platform"]}.'
+            'Platform lookup failed; platform is a subshell to be evaluated: '
+            f' Task: {task}, platform: {task_spec["platform"]}.'
         )
     return platform