Request Data - Attachments with not permitted characters

Hello everyone.

I’m testing attachments adding in Nintex Workflow 2010 (with Request Data action) on SharePoint 2010 Foundation.

I am encountering an error when I try to attach file with not permitted characters (eg. “&”).

Server Error in '/' Application.
The file or folder name contains characters that are not permitted. Please use a different name.

 

 

After that the workflow has Status “Completed” but Outcome is “Pending”.

When I try to edit that task and Complete it again the following error occurs:
Server Error in '/' Application
This task is currently locked by a running workflow and cannot be edited.

 

The problem is that the workflow hangs and I cannot do anything with it.

Do you have any ideas how to unlock the failed workflows or how to prevent from locking?

 

Thanks in advance for any information!