"502 Bad Gateway" - Resolution

HTTP Error 502.1 – Bad Gate way
In this situation, IIS sends a request to the specified CGI process, and then IIS waits for a response. If IIS does not receive a response from the CGI process within the configured CGI time-out period, you receive the error message that is mentioned in the "Symptoms" section.
Server Error in Application "application name"
HTTP Error 502.1 – Bad Gateway
HRESULT: 0x00000000
Description of HRESULT The CGI application exceeded the time allowed for processing and the process was shut down.       
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Fix :

 > Start > Run > inetmgr> OK.
 > Expand server name > expand Web sites > and then click the Web site that you want to modify.
 > In Features view, double-click CGI.

 > Type the appropriate time-out value in the Timeout (hh:mm:ss) text box, press ENTER, and then click Apply.

OR
Make PHP run as ISAPI rather than CGI.
   >Login to plesk
   > domain administration page
   >. Setup -> Services -> PHP Support
   >. make sure "run as ISAPI extension" is checked
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