This appears to be the same as (or similar to) issue #3609.In my case, when I close a task from /scp/tickets.php (in other words, when working with a task assigned to a ticket), the "Loading" message displays, the task is updated accordingly, but the "Loading" message is never dismissed. This even occurs if I don't fill in a response and the validation fails (so a validation error is visible on the Post Update tab of the task).I have not been able to track down the source of the problem, yet.