I’m trying to add new theme, but whenever I press ‘Finish Theme’ (submit) button at the [Submit a New Add-on > Theme generator] page, it says ‘Bad Request’ and nothing happens. What is the problem in this case?
I think I found the reason. The error occurs when the name of a theme contains the word ‘Firefox’. There are many theme with names containing the word ‘Firefox’ so I thought it is okay, but it seems that putting firefox to a name of a theme is blocked after that 
Can you please file an issue here: https://github.com/mozilla/addons/issues
While we don’t allow “Firefox” on names in most cases, that kind of error is not the way we should surface it.
I thought the same thing because I didn’t know what to do when it only says Bad Request but no information about what was the problem.
I’ll do it when I’m free. Thanks 