Steps to Reproduce:

1) Create the issue in the specific project.
2) Change the Reporter to other UserName and Stop watching the issue.
2) Navigate to Browse Project Page--> Activity Stream
3) The change Reporter activity is seen in Activity Stream

Expected Result:
1) If the Vote button is clicked, the voting of the issue should be successful and the same should be displayed in View Issue screen.
2) If the Watch button is clicked, the user should be added as watchers of issue and the same should be displayed in View Issue screen.

Actual Result:
1) The error message is displayed as 'An unknown error occurred while voting.'
2) The error message is displayed as 'An unknown error occurred while adding you as a watcher.'

Observation:

We are getting same issue in the Activity Stream Dashboard gadget and Activity Stream in the User Profile page.

Please find the attached document for your reference.