On Plesk for Windows, MailEnable WebMail, myLittleAdmin and/or default website stops working: Error 503 Service Unavailable

Symptoms

• On a Plesk for Windows server, MailEnable WebMail, myLittleAdmin and/or default website stops working:

  CONFIG_TEXT: Error 503: Service Unavailable

• The corresponding application pool (MailEnableAppPool, sqladmin(default) or DefaultAppPool) is stopped in Server Manager > Tools > Internet Information Services (IIS) Manager > server_hostname > Application Pools.

• After starting the application pool and accessing a website in the browser, one of the following error messages is found in Event Viewer > Windows Logs > Application:

  CONFIG_TEXT: The Module DLL C:\Windows\System32\inetsrv\pleskurlprotection.dll failed to load. The data is the error.

  CONFIG_TEXT:The Module DLL C:\Windows\System32\inetsrv\pleskrepairmodule.dll failed to load. The data is the error.

• The parameter Enable 32-Bit Applications is set to True in Internet Information Services (IIS) Manager > server_hostname > Application Pools > pool_name > Advanced Settings...:

  

Cause

Enabled parameter Enable 32-Bit Applications causes incompatibility.

Resolution

1. Connect to the server using RDP.

2. Open Internet Information Services (IIS) Manager:

   • in Windows Server 2008 and 2008 R2: go to Start > Administrative Tools > Internet Information Service (IIS) Manager.
   • in Windows Server 2012 and newer: go to Start > Server Manager > Tools > Internet Information Service (IIS) Manager.

3. Go to server_hostname > Application Pools, select MailEnableAppPool and click Advanced Settings... in the right pane.

4. Switch the parameter Enable 32-Bit Applications to False and click OK to save the changes.

5. Repeat the steps 3-4 for myLittleAdmin (pool name is sqladmin(default)) and/or default website (pool name is DefaultAppPool) if necessary.