Motoko-chan,
I'm one of those people who can't seem to get the install or upgrade tools to work through my webhost because of failed uploads, but I can always do the manual approach just fine by first downloading to my home computer and then, second, ftp-ing all the files to my website.
QUESTION: Will the upgrade tool allow me to ftp the upgrade ZIP file myself to my forum folder along with the upgrade.php and, then, will the upgrade.php be able to process the ZIP (or unzipped) files since they'll already be uploaded there together in the same initial forum folder?
Again, the upgrade.php doesn't seem to be able to get through my webhost to upload files, so this way I'll put the ZIP file there for the upgrade tool to use myself with my ftp which always works, and the problem (actually, for many of us who have this problem) of uploading files with the upgrade tool will be bypassed and solved.