When I try to change my avatar picture an error occurs ("Bad Request - Unknown error happened: is_image() takes exactly 2 arguments (1 given)") and nothing happens :-(
Thank you for your report, I've been able to reproduce this issue and have passed it to the developers. Sorry for the inconvenience.
Thank you! Please send a short note when the changing of the avatar picture works.
This issue has now been fixed.
Great! Thank you for the pretty fast fix! I've tested the upload and everything worked out very well ...