Symptoms
-
Updating Plesk Obsidian for Windows fails:
Error: The installation of the package 'modsecurity' failed with code 1603. (upgrade: Upgrading ModSecurity IIS Module...)
-
Creating new domains or subdomains in Plesk fails:
Domain example.com creation failed
String must not be empty
.....
Cause
ModSecurity modules were manually removed from IIS - they are missing in Internet Information Services (IIS) Manager > server_name > Modules.
Resolution
-
Connect to the server using RDP.
-
Go to Start > Server Manager > Tools > Internet Information Services (IIS) Manager.
-
Register ModSecurity modules:
-
Restart IIS by opening CMD as Administrator and executing the command:
iisreset /restart
-
Complete the update or create a domain/subdomain anew.
Additional information
Instead of removing ModSecurity modules directly from IIS, ModSecurity can be disabled via Plesk: How to disable ModSecurity in Plesk?