If you see this kind of error ( 500 error), then your web server encountered an unexpected condition that prevented it from fulfilling the request by the client for access to the requested URL. This is a 'catch-all' error generated by your web server. Basically something has gone wrong, but the server can not be more specific about the error condition in its response to the client. In addition to the 500 Internal Server Error notified back to the client, the Web server should generate some kind of internal error log which gives more details of what went wrong. It is up to the operators of your Web server site to locate and analyse these logs.
Any client (e.g. your Web browser or our CheckUpDown robot) goes through the following cycle when it communicates with your Web server:
Obtain an IP address from the IP name of your site (your site URL without the leading 'http://'). This lookup (conversion of IP name to IP address) is provided by domain name servers (DNSs).
Open an IP socket connection to that IP address.
Write an HTTP data stream through that socket.
Receive an HTTP data stream back from your Web server in response. This data stream contains status codes whose values are determined by the HTTP protocol. Parse this data stream for status codes and other useful information.
This error occurs in the final step above when the client receives an HTTP status code that it recognises as '500'.
Resolving 500 errors - general: this error can only be resolved by fixes to the Web server software. It is not a client-side problem. It is up to the administrators of your Web server site to locate and analyse the logs which should give further information about the error.
See more at http://goo.gl/juYFb