Never assume anything, test everything
All these years I assumed that Assembly.Load() would respect version numbers if specified in the FullName string. As I?ve been adding more test coverage to Microsoft.Activities I found that Assembly.Load does not work that way.
Suppose you have an assembly named ActivityLibrary and you deploy V1 but you try to load V2
To force Assembly.Load to respect the version number you must sign the assembly
So be careful out there and sign your assemblies.