It won't let me upload a cover image for my project. My image is the suggested size of 630 x 500. I have tried it as PGN and JPEG. I have tried versions which are 274, 110, and 84 KB in file size. I have tried uploading from Chrome and from Microsoft Edge. I have tried to upload from my computer and from Dropbox. Every time I try, it says "There's an issue with the file you selected. Please edit your image or try another one. Server failed to respond, please try again later." I have tried on multiple days. The last time I uploaded a project the same thing happened. What do I do?

That's really bizarre. 

 Required (Minimum: 315x250, Recommended: 630x500)

It shouldn't give you an error message regardless of if it's a JPG or a PNG, but maybe it is something to do with the dimensions? 

If you could provide screenshots it would be a lot clearer, but contact support if the problem persists.