We have a fairly new project (although with a fair few custom usercontrols and razor macros) based on Umbraco 4.7.2. The project is stored in a git repository.

If I just checkout the code and do the upgrade procedure to 4.9.1 (override bin/, umbraco/ and umbraco_client/ and add install/ from the 4.9.1 zip) it works fine – I can go through the upgrade procedure and the site then works as long as I don't compile.

But as soon as I try to rebuild/recompile the code with the 4.9.1 binaries and files, before or after going through the upgrade procedure above, I get the following error:

Parser Error Message: Could not load file or assembly 'CookComputing.XmlRpcV2, Version=2.2.0.4, Culture=neutral, PublicKeyToken=null' or one of its dependencies. The located assembly's manifest definition does not match the assembly reference. (Exception from HRESULT: 0x80131040)

(full message)

I can try to fix this error by simply replacing the new CookComputing.XmlRpcV2 binary with the old one from 4.7.2, and this seems to make it get further, but then I get the following error:

               Method not found: 'System.String umbraco.interfaces.IApplication.get_Alias()'.

(full message)

Has anyone else encountered this? Do you know what I could do about it?

Robin