Cannot create an add-in. An add-in adapter was loaded into the host's appdomain, which can cause subtle problems involving ...

Cannot create an add-in.  An add-in adapter was loaded into the host's appdomain, which can cause subtle problems involving loader contexts.  Ensure the add-in adapter doesn't exist alongside the host's executable or hasn't been otherwise loaded.  Add-in Adapter assembly: "{0}"  Expected location: "{1}"
We loaded the assembly from the following locations: {2}