I have been testing migration bug Bugzilla, and I seem to get errors when it comes to certain types of icon attachments. At first I thought it was only via API and was some base64 encoding issue or something but if I go to https://bugzilla.wikimedia.org/show_bug.cgi?id=40186 and download the `Wiktionary Logo (mini).ico (1.84 KB, image/x-icon)` attachment and try to upload it to any 3 of the phab instances I have at the moment get the same issue:
{F234994}
Attachment should link direct: https://bugzilla.wikimedia.org/attachment.cgi?id=11105
This seems to happen for some, not sure if all, attachments of type .ico ( image/x-icon and image/icon)