I have a few workflows in three different site collections which are erroring or failing with this email notification. The workflow details are all green and it shows the workflow fully completed successfully. The workflow actions result in perfect data -- nothing is missing or incorrect. This is the email I get:
"The [x] workflow has ended unexpectedly.
An error has occurred in [x].
Click here to view the workflow status."
I opened a Nintex support ticket just now, however I'm wondering if anyone else has a solution? I saw a similar issue thread here, but it looks to be slightly different: https://community.nintex.com/message/22534#22534