The files are normal size jpegs. Batch uploading new versions of existing files can't be done in commonist, which is what I usually use, without overwriting the file description.

that's an encoding problem, those are the items with things like à, ö or é in the title.
I'll do these manually but is this a fault on my end or yours? How could this be avoided in the future?

thank you!

They failed because there was a í in the filename.

I've found the culprit. I had adblock on. :S

I;m arround atm

So, if I read the log correctly there are 5 files that failed, 1518 that succeeded.

Dereckson was so kind as to lend me some hosting space.

oh, and, yes file description txt files are included in the zip file.

see https://bugzilla.wikimedia.org/show_bug.cgi?id=73549