Community Tip - Did you know you can set a signature that will be added to all your posts? Set it here! X
Attempting to add large files to the case logger while opening a new case is failing (or timing out) during the scanning process that appears to happen after the upload has finished. I've tried both 7zip (295 MB) and zip (319 MB) and both fail the same way. According to the note on this page, up to 2 GB files should be supported.
What's odd is that removing the problem attachment from the attach files screen and then finishing case creation shows that both files were actually attached after all. This would seem to indicate that whatever scanning is happening does eventually finish, but it's taking longer than the timeout on the attach files page.