As the error seems to be related to workflows and the ability to clone, I can think of the following possible causes, depending on the action which triggered the error:
Reviewing the underlying workflow in edit mode may provide a clue.
If you do not find anything else, I'd suggest you to create a ticket with Atlassian Support:
Over the next several weeks we'll be sharing some of our Getting Started guides here in the community. Throughout this series of posts, we'd love to hear from customers and non-customers ab...
Connect with like-minded Atlassian users at free events near you!Find a group
Connect with like-minded Atlassian users at free events near you!
Unfortunately there are no AUG chapters near you at the moment.Start an AUG
You're one step closer to meeting fellow Atlassian users at your local meet up. Learn more about AUGs