Some users reported that, when accessing Choralplayer, an message like this was returned:

Bad Request

Your browser sent a request that this server could not understand.
Size of a request header field exceeds server limit.

Additionally, a 400 Bad Request error was encountered while trying to use an ErrorDocument to handle the request.

This problem is typically caused by the cache or by the cookies of the browser: they got corrupted somehow, and submitted a request that cannot be accomplished by the Choralplayer server.

The solution is quite simple: clear the cache and/or the cookies of the browser used. A useful guide to clear cache and cookies for various browser types is available here .

An alternative solution is to use, at least temporarily, another browser. So, for example, if you normally use Google Chrome, temporarily use Mozilla Firefox or vice versa. The cache and the cookies of the browser affected by the problem will likely expire after some time, and you can use that browser again then.