Register C# DLL prompt: it is not a valid .NET assembly

Problem: RegAsm: error RA0000: Failed to load ‘XXX. DLL’ because I
t is not an valid.NET assembly.
It turned out that the FramWork version was too low, so updating It was the solution.
 

Reproduced in: https://www.cnblogs.com/PengRay0221/p/9140327.html