I open commit on github here:
While trying to change profile pics in this forum, if i accidently tried upload gif images which are over the 256KB size limit, I am not getting any error messages, it just stays there, means the upload window simply stays there with no message. Take a look at the screenshot where I tried to upload a GIF image of 512KB, and there is no error message like "uploaded pic should be under 256KB" or anything.
The gravatar option is awesome but @julian suggested to me that many people did not like the Gravatar option. My suggestion is to not remove this in future updates, but to keep it as an optional feature inside ACP. Because availability of gravatars is awesome since millions make use of it and it is way better than the default image. Gravatars is popular among bloggers, so will come in handy for some people
Did you not get an error box pop up in the top right corner?
If you use the imgur plugin, you would get an error along the lines of "Entity too large". If you use local uploading, I'm not 100% on how it handles errors. I thought it was the same way, I'll load up my dev environment and test it.