Unable to set avatar/profile picture, various errors

I'm not sure whether this is the right place to post this, but I'm having problems setting my profile picture. I get 2 different error messages:

• When I upload the picture and hit save: TypeError: NetworkError when attempting to fetch resource.

• When I upload the picture and don't do anything after: SyntaxError: JSON.parse: unexpected character at line 1 column 1 of the JSON data

  (The console says the error happened in handleImageUpload)