I've just overwritten the entire VSADMIN folder including sub-folders and files likewise, JS folder and files with those contained in v7.7.1 and the problem is the same. Also tried v7.7.2 and same result.
BTW, I've also re-run updatestore.php now for the 7.7.2 version.
Hi David Sorry for the wild goose chase but I think I see what is happening now and I've added the fix to the vsadmin/doupload.php file in the updater. What seems to be the problem is that if there are any spaces or additional characters in your includes.php file or the database connection file then the "SUCCESS" doesn't match and the code thinks an error occurred. I've added a line to flush the output buffer and that should sort it out.