I have actually had the same thing happen on linux servers but normally just waiting it out seemed to resolve it. Had to try it a couple of times but it would go through eventually. I think I went away and did something else for about 1/2 an hour, came back and refreshed the page and was upgraded.
Installing and upgrading help
Moodle hanging on upgrade to 2.6 or 2.7
This discussion has been locked so you can no longer reply to it.