hey Michelle, this means that either your new avatar is too big pixel wise or too big file size wise - you'll have to shrink the picture/photo to a smaller size (the parameters should be displayed when you are updating your avatar)
Hope this helps
I've been having this issue as well.
The dimensions are: 315x315 and the size is only 70.9KB. Is that still too large of a file?
I believe the max size you can have is 150x150 so will need to shrink it a little
That would explain it then! Thanks!