C # encounters which has a higher version than referenced assembly

When C # encounters this hint: which has a higher version than referenced assembly,

Indicates that there are different versions of DLLs that have two or more project references.

Such as:

A project reference log4net version is 2.0;

B Project Reference log4net version is 1.8;

A similar problem arises when a and B projects are eventually used simultaneously in the same start-up project.

Workaround: Change them to refer to the same version of the DLL.

C # encounters which has a higher version than referenced assembly