Hello finally able to resolve it:
Issue : Troubleshoot .NET package mix ups on Linux - .NET
refer this :
https://github.com/dotnet/core/issues/7699
Thanks now its working.
The execution of post-install.php has failed with the following message:
226031:63f8d4edc565c ERR [extension/dot-net] Execution installer has failed with exit code 1, stdout: , stderr: curl: (6) Could not resolve host: packages.microsoft.com
Unable to get package repository source.