Not able to upload profile image for the forum

Today I tried to upload my image on this forum and its not making me to upload the pic…firstly it pings me an error of “Not a square Image” …so I made my image square…but still it wont uploaded…I check the console via firebug and seems to be getting error like -

502 Bad Gateway -

I replaced the authenticity_token BTW from original one, let me know how can I fix this ?