The framework 'Microsoft.NETCore.App', version '2.0.0' was not found.

Building my project works in ubuntu 20.04 but when I try to run I get the following error.

The framework ‘Microsoft.NETCore.App’, version ‘2.0.0’ was not found.

Anyway around this? I don’t think you can download the 2.0 frame work anymore from MS website.