What http error? That's important. An error like 403 means that you shouldn't know that URL - it's not meant for the public to access, it's meant for the site to send certain people (probably those logged in or those administering the site) to.
If it's a 500 error, the site has a problem - 500 means "server error", and the site developer has to look in the server log to see what's causing what problem where.
404, of course, is the old "page not found error", and whoever developed the site shouldn't allow that - it should redirect you to a nice looking page telling you that the page you were looking for doesn't exist.
But without knowing the error number, we can't tell you what's happening. (Except that it's probably not anything to do with your phone.)