Application pools are crashing on Plesk for Windows Server: The Module DLL C:\path\to\module_name.dll failed to load. The data is the error.

Symptoms

• Plesk and websites are unavailable with the following error message in a web-browser:

  PLESK_INFO: 503 Service unavailable.

• Application pools are stopped in IIS Manager > Application pools.

• After restarting an application pool of the website and accessing this website, the application pool crashes.

• The following error message is logged in Windows Event Viewer > Windows Logs > Application:

  PLESK_INFO: The Module DLL C:\path\to\module_name.dll failed to load. The data is the error.

Cause

The module defined in IIS configuration is improperly configured.

Resolution

1. Connect to the Plesk server via RDP.

2. Start a Command Prompt as an Administrator.

3. Create a backup of IIS configuration:

   C:\> %windir%\system32\inetsrv\appcmd.exe add backup BeforeEditBackup

   Note: The backup will be created in C:\Windows\System32\inetsrv\backup.

4. Start Internet Information Services (IIS) Manager at Windows Start > All Programs > Administrative Tools.

5. In IIS Manager, click on SERVERNAME > Modules and remove the faulty module reported in the error message.

   Note: In case the module is not visible on the modules page, move to step 6.

6. Open the file %windir%\system32\inetsrv\config\ApplicationHost.config in a text editor and remove the lines related to the faulty module (if exist).
   For example:

   CONFIG_TEXT: <add name="CSPms" image="C:\Inetpub\CSPGateway\CSPms.dll" />

7. Save the changes.

8. Restart IIS:

   C:\> iisreset