Might it be an issue with enough free space on the disk to properly update? My COH2 wouldn't update the 2.3 GB patch without 17.5 GB free on disk.
I deleted something to give it space and it seemed to try to start update but then froze my pc (which never happens) once recovered it then complained there still wasn;t actually 17.5 gB free and I had to delete something else after which it worked fine
