I just repro'ed it by assigning a string to the @url instance variable.
Make sure your controller/helper/view code is NOT assigning to @url
anywhere (either directly or indirectly).
link_to/url_for and related uses the ActionController::Base @url
instance variable to generate URLs, so if you (or plugins you've
installed) clobber it somehow, you'll get this error.
Al Evans wrote: