Error 500 during upload files

1. Open issue in issue tracker
2. Press "More" \ "Attach files"
3. Select several files
4. Press "Attach"

I've got:

• error page 500 (debug info: 97e738109fd249c197a82d8eefe6ce6d)
• all files or part of files attached (after reopening page)
• created comment with list of part attached file names (not all of them)

Browser: Google Chrome 31.0.1650.57 m