In Issue tracker, if you try to attach an attachment in Edit/Add issue,
the operation will fail with an error 500.
ajax/EditIssue.php?action=edit 500 (Internal Server Error)
Possible permission issue with IssueTrackerDataPath.
@kongtiaowang can you make sure the paths are valid ?
This bug seems to be specific to the test VM.
It has been fixed on testing VM.