This is actually the strangest problem of my existence, and should not even Google it. It's happening with an Apache powered website designed in PHP, which utilizes mod_rewrite (but that is not the problem, I attempted getting rid of the .htaccess file, problem still is available).

If I've got a query string that appears exactly or much like: =/id I recieve an 501 response:

Method Not Implemented

Reach / not supported.

Furthermore, a 404 Not Found error was experienced while attempting to make use of an ErrorDocument to handle request.

I never written such error page, never sent an 501 response, not have the smallest clue where this factor is originating from. Initially I'd a lengthy URL giving us a similar error, however i removed lower for this little snippet above. Basically remove or change any character, the error's gone.

In the event that helps: this site is, and also the original URL was an openid login request which appears like this:

that the query string is:


I requested the support team, plus they stated it had been mod_security, and disabled it for this site. And today it really works fine. I ought to have began with this. Anyway, interesting help.

Maybe should you take away the error you receive with no GET parameter first

After which urlencode your query

Urlencode your query string parameter(s). becomes works fine, so HerrSerker already clarified your question.