If you have a redirection – let's say because content object renaming – with a querystring, the querystring will be lost.
The file index.php.diff was given as fix suggestion.
1 - open some url my.site/object?config=foo in frontend
2 - in backend, rename the object to object2
3 - reload the url from point 1
4 - site redirects /object -> /object2, but the querystring is lost.