Article ID: 116928, created on Aug 26, 2013, last review on May 15, 2014

  • Applies to:
  • Plesk 11.5 for Windows


Error "HTTP Error 503. The service is unavailable" appears while opening Paralels Plesk Panel.

The following error is in Windows Event Viewer > System log:

Application pool 'DefaultAppPool' is being automatically disabled due to a series of failures in the process(es) serving that application pool.

And the following error is in Windows Event Viewer > Application log:

The Module DLL 'C:\Program Files\Common Files\Microsoft Shared\Web Server Extensions\15\isapi\spnativerequestmodule.dll' could not be loaded due to a configuration problem. The current configuration only supports loading images built for a x86 processor architecture. The data field contains the error number. To learn more about this issue, including how to troubleshooting this kind of processor architecture mismatch error, see


Parallels Plesk Panel application pool is working in 32-bit mode. Global (i.e. applied to all application sites on all application pools) ISAPI module spnativerequestmodule.dll (SharePoint 2013) is a 64-bit application. Attempt to load 64-bit application on 32-bit application pool is not possible, which causes application pool to fail on start-up.


IIS 7.x can load global ISAPI modules conditionally, depending on application pool's settings:

  1. Open Command Prompt (Start > Run > cmd.exe).

  2. Type these commands:
cd %systemroot%\system32\inetsrv
appcmd.exe set config -section:system.webServer /globalModules /[name='SPNativeRequestModule'].preCondition:integratedMode,bitness64
  1. Restart Control Panel service using Parallels Plesk Panel Services Monitor.

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Error 503. The service is unavailable


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