After a user upgraded the Windows operating system to the latest feature release, the user...

When a legacy application is not fully functional after upgrading the Windows operating system, the first step to troubleshoot the issue is to:

Run the application as Administrator: Legacy applications often require administrative privileges to run correctly. Running the application with these privileges can resolve issues related to permissions and access to certain system resources.

Raise the User Account Control level: This increases security prompts but does not resolve compatibility issues.

Turn off Windows Defender Firewall: This can expose the system to security risks and is unlikely to resolve application functionality issues.

Disable compatibility mode for the application: Compatibility mode should generally be enabled for legacy applications to ensure they run properly on newer OS versions.