title: How to stop error 400 when URL contains a percent % symbol? (Apache)
body: <p>Is there a simple way to prevent a server from returning an error 400 (bad request) when a URL is requested containing a percent % symbol?</p>
  
  <p>Many major sites have this same problem, for example: <a href="http://twitter.com/%" rel="noreferrer">http://twitter.com/%</a> or <a href="http://bing.com/%" rel="noreferrer">http://bing.com/%</a></p>
  
  <p>But other sites have fixed this and return a custom error page instead, rather than the standard server response, such as: <a href="http://facebook.com/%" rel="noreferrer">http://facebook.com/%</a> or <a href="http://google.com/%" rel="noreferrer">http://google.com/%</a></p>
  
  <p>Is there a simple, single way to escape a single character % symbol from returning a 400 error, but instead, returning a 404 error using a custom error document using mod_rewrite or similar in Apache?</p>