What is the bug in MonoDevelop?

Question

Mono

How to fix error - C:\Windows\Microsoft.NET\Framework\v4.0.30319\Microsoft.Common.targets(5,5): Warning MSB3644: Framework reference assembly '.NETFramework,Version=v4.5' not found. To fix this error, install the SDK or addressing package for this version of the framework, or change the target application framework to the version for which the SDK or addressing package is installed. Note that assemblies will be resolved from the Global Assembly Cache (GAC) and will be used instead of reference assemblies. Therefore, they may incorrectly use the selected infrastructure as the target. (MSB3644) (jk) What should I do?

Answer 1

Option one - abandon monodevelop, since it is no longer supported, and switch to VS / VS Code / Rider
Option two - do as requested, and install Devpack of the required version.