- Plesk for Windows
Sometimes, after a Plesk upgrade procedure, the Plesk or client sites do not work correctly due to problems with third-party or Plesk ISAPI filters.
The error HTTP Error 500 may be seen while browsing a website or using Plesk on Windows.
The following error is shown when attempting to open a site on the server:
PLESK_INFO: HTTP Error 500.0 - Internal Server Error Calling LoadLibraryEx on ISAPI filter "C:\\Parallels\\Plesk\\isapi\\isapirewrite4.dll" failed
PLESK_INFO: Failed to run command 'cmd /C ""C:\\Program Files (x86)\\Parallels\\Plesk\\bin\\ipmanage.exe" --xml-info"' Exit code: 1
ISAPI filters can be global, for all IIS sites or local sites, or for specific IIS sites.
- Connect to the server using RDP;
Note: if direct RDP access to the server is not possible, contact server administrator for further assistance.
- Check the installed global ISAPI filters in the Internet Information Server (IIS) Manager:
Then, check the file that the existing ISAPI filter refers to:
Users psacln and psaadm have no explicit prohibition (deny) for reading and execution of this file:
For the Plesk site, separate ISAPI filters should be installed.
A "Rewrite" filter should be installed as a minimum, with reference to the
All files to which the Plesk ISAPI filters refer should include reading and executing rights for the users psacln and psaadm , and NETWORK SERVICE should be explicitly installed: