Hello Matteo,
by "mixed mode" it is meant an assembly written in both pure .NET code and not native .NET code.
You can try to launch PEVerify tool on your assembly to check which kind of warning\error are returned, fix them and re-protect the new assembly with Envelope, it should no longer complain about errors if PEVerify passed successfully. In any case, such Metadata validation messages are just warnings to inform that the assembly is a mix of pure .NET code and not pure .NET code.
Hope this clarifies.
Ilaria
by "mixed mode" it is meant an assembly written in both pure .NET code and not native .NET code.
You can try to launch PEVerify tool on your assembly to check which kind of warning\error are returned, fix them and re-protect the new assembly with Envelope, it should no longer complain about errors if PEVerify passed successfully. In any case, such Metadata validation messages are just warnings to inform that the assembly is a mix of pure .NET code and not pure .NET code.
Hope this clarifies.
Ilaria