Recently i have tried to upload some screenshots to your Phabricator instance (PureOS Tracker) and it always throws that your Phabricator have not a configured storage engine to save the files but, i believe some people have uploaded some screenshots on others times.
I seem to recall mentions of filesize related to this: How big were the files you tried but failed to upload?
Please try with files of a smaller size (e.g. resample in Gimp) - and report back here whether that helped.
Hey Theo, can you maybe add a storage engine to our Phab instance?
Just having flatfile storage should actually be sufficient. I can not add this myself because I think I lack permission on the server itself (and that is needed to change this setting).