Plesk shows 503 Service Unavailable: iisnode.dll failed to load The data is the error

Symptoms

• When loading Plesk the following error is displayed:

  HTTP Error 503. The service is unavailable

• In Event Viewer > Windows Logs > Application the following error:

  The Module DLL C:Program Files (x86)iisnodeiisnode.dll failed to load. The data is the error.

• PleskControlPanel Application pool is stopped at IIS Manager > server > Application Pools

Cause

Plesk users psaadm and psacln do not have access to
C:Program Files (x86)iisnode
directory by default.

Resolution

1. Connect to the server via RDP.

2. Add the following lines into the disksecurity.xml file which is stored in %plesk_dir%etcDiskSecurity directory:

   <!-- Program Filesiisnode -->
    <Entry AccounType="1" Account="Psaadm" Path="{ProgramFiles}" SubPath="iisnode" AceFlags="ThisFolderSubfoldersAndFiles" AccessMask="Read" EntryFlags="0x40" />
    <Entry AccounType="1" Account="Psacln" Path="{ProgramFiles}" SubPath="iisnode" AceFlags="ThisFolderSubfoldersAndFiles" AccessMask="Read" EntryFlags="0x40" />

3. Open Plesk Reconfigurator by running the following command in cmd:

   C:> “%plesk_dir%adminbinreconfigurator.exe”

4. Correct disk permissions:
   
   OR
   Repair Plesk Installation > tick checkbox Plesk File Security > Check.

5. Start Plesk Services Monitor:
   

6. Restart Plesk Management Service
   

7. Start PleskControlPanel application pool at IIS > server > Application Pools > PleskControlPanel > Start