Can you provide further details? File size? What is it? What error box occurs? Etc?A zip file. It says "There was a problem uploading your file." What is wrong?
Aw yis, it worked. Thanks, I searched the error message and found a post in XF community says it's flash uploader, but I thought it was server setting or something which I can't disable.I had a similar problem earlier today. I solved it (temporarily) by going to my Preferences, and UN-checking the option to Use the Flash-based loader for attachments. Be sure to save your changes.
Hopefully this will help you in the meantime.