If you are using a Windows 2008 server, running Plesk 8.6, you might encounter this error on Horde:

502 - Web server received an invalid response while acting as a gateway or proxy server.There is a problem with the page you are looking for, and it cannot be displayed. When the Web server (while acting as a gateway or proxy) contacted the upstream content server, it received an invalid response from the content server.


1. You need to see the complete details of what is happening in your IMP server. Browse locally or from the server to http://localhost:8425/.

2. Check if CGI Role Service is installed in IIS: Server Manager > Roles > Web Server > Role Services

3. Uncomment the following files on the PHP configuration file from %plesk_vhosts%\webmail\horde\php.ini. - php_fileinfo.dll, php_mysql.dll and bphp_mysqli.dll

4. Do no forget to set cgi.force_redirect = 0 in %plesk_vhosts%\webmail\horde\php.ini.

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