--- a/eric6/Plugins/CheckerPlugins/SyntaxChecker/pyflakes/messages.py	Sun Jan 03 15:31:46 2021 +0100
+++ b/eric6/Plugins/CheckerPlugins/SyntaxChecker/pyflakes/messages.py	Thu Jan 07 17:22:16 2021 +0100
@@ -685,6 +685,8 @@
         @param error error details
         """
         Message.__init__(self, filename, loc)
+        if not isinstance(error, str):
+            error = str(error)
         self.message_args = (error,)