Hi @adil,
This error message usually occurs when the required version of the .NET Framework is not installed on your computer. Here are some steps you can try to resolve the issue:
1.Open the Control Panel and navigate to Programs and Features. Look for the installed versions of the .NET Framework. The updated SharePoint Server requires the use of version 4.8 of the .NET Framework.
You can click here to download .NET Framework 4.8.
2.If your version of .NET Framework is fine, then check the following to see if it works. If something is wrong, then you can use the .NET Framework Repair Tool to fix this .NET Framework.
3.Make sure that your Windows operating system is up-to-date. Go to Settings > Update & Security > Windows Update and check for any pending updates. Install all the available updates and restart your computer.
4.Restart your SharePoint 2019 server in IIS.
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