[BUG] Define assignee in a ticket raise an Error

[Kaio Cristian Costa Porto De Magalhães]

When i try to define one developer to the ticket an error was raised, and a msg was shown.The message is only an 'Error' in the right foot of the page.

http://www.clipular.com/c/4811770044612608.png?k=18FNPwCrcHrrGdnmTWqSFInJjOI

Sorry for my poor english, i don't write very well.