The error comes from the fact that the typeconverter dll also contains specific .NET types, like enums, am I correct? As you have fields defined with those types, it needs to load the types. You indeed should first use the old type converter assembly to load the project, remove the type converter, then save again, or place the types in a separate assembly (with the same namespaces and signature) and select that assembly when the dialog pops up during project load to look for additional assemblies as it can't find a specific assembly.
In v2.x this is unfortunately the only way, as the deserialization is done by .NET and our code starts after the whole project file is loaded. If you really can't get it working and don't have any sourcecode of the types anymore, let us know, and we'll see if we can resurrect your project in a debug build of the designer. The main thing is, IF you still have the .net types which are defined by the typeconverters, that's the main solution. You can reply to this message to re-open the thread
