How to get BinaryFormatter to deserialize in a different application

If the classes are the same, and it's just another assembly, you could try adding an assemblyBinding section to you .config file.

You should also read the article about Resolving Assembly Loads and the TypeResolve event.

Using these techniques you can redirect the .Net typesystem to another type while deserializing.

Note: Migrating your shared classes to a shared .dll will be a more easy solution.

You can achieve it by using custom SerializationBinder. See here: Advanced Binary Serialization: Deserializing an Object Into a Different Type Than the One It was Serialized Into