HTTP Error 502.3 - Bad Gateway

Question

I created wcf service and host it on iis trying to browse .svc  i'm getting this error i watsed one day but it's not resolved please help me to get out from this issue.

 

Most likely causes:

• The CGI application did not return a valid set of HTTP errors.
• A server acting as a proxy or gateway was unable to process the request due to an error in a parent gateway.