Lots of 500.shtml page not found errors in logs I've been getting lots of page not found errors for  500.shtml in my logs. A lot of them seem to be originating from search spider and ho I might be able to fix these, I'm curious to why 500.shtml is even being sought out in the first place and how these are being generated at such a furious pace:

   type: page not found
   location:http://www.example.com/test.html
  referrer:
 message: 500.shtml
 severity: warning
  hostname: 


500.shtml entries in the Drupal logs. In many cases, these are generated by search engines (determined by doing reverse lookups on the IP's), sometimes from users (but in very few cases). How can I fix it?
The 500 error page is show when the server has an internal error.  

Your server is looking for a file named 500.shtml because a directive set that as the page that must be shown when the server has an internal error. The .htaccess file used by Drupal set the page for the "page not found" error to /index.php with the directive ErrorDocument, but it doesn't set any error page for any 500 codes, which is the set by the server using a different file; for Apache, this means the access.conf file, or any files included by that file.

For what can cause an internal error, it could be a server directive, or a wrong argument passed to such directives. Other causes could be:


directory permissions
file permissions
a wrong transfer mode used when transferring the Drupal PHP files to the remote server when using FTP
the line endings of the files that don't match the one used from the Operating System that is hosting the server