diff --git a/test/functional/test_framework/util.py b/test/functional/test_framework/util.py
index 903dd1b2b5b..c35d41124dd 100644
--- a/test/functional/test_framework/util.py
+++ b/test/functional/test_framework/util.py
@@ -101,10 +101,9 @@ def assert_raises_message(exc, message, fun, *args, **kwds):
     except JSONRPCException:
         raise AssertionError("Use assert_raises_rpc_error() to test RPC failures")
     except exc as e:
-        if message is not None and message not in e.error['message']:
-            raise AssertionError(
-                "Expected substring not found in error message:\nsubstring: '{}'\nerror message: '{}'.".format(
-                    message, e.error['message']))
+        if message is not None and message not in repr(e):
+            raise AssertionError("Expected substring not found in exception:\n"
+                                 f"substring: '{message}'\nexception: {repr(e)}.")
     except Exception as e:
         raise AssertionError("Unexpected exception raised: " + type(e).__name__)
     else: