The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)
This new compile error was driving me mad! My project used to work, then I upgraded to a newer version of ECO. There were 3 projects using an EcoSpace, 2 would compile but not the 3rd. In the end the solution was simple but annoying to track down so I thought I'd mention it here just in case anyone ever strolls across it and finds it useful. In my licenses.licx files for the 2 projects I had the line Eco.Handles.DefaultEcoSpace, Eco.Handles but in the project that was failing somehow a strong name had been used, even though I originally entered it manually! Changing it back to the weak name fixed the problem.