@Bri it seems to be related to 2 critical settings for uploads, avatars have there own maximum size while profile headers use the maximum size for any upload that should go in posts
@baris, can you take a look? The error message passed back from imagemagick suggests the command was called incorrectly. On Ubuntu 14.04, I have imagemagick v6.7.7.10 installed
@raven Please let me know the output of uname -r && lsb_release -a. Please also try to upgrade your imagemagick installation if possible.