The XOOPS Upgrade may need to write to files that have previously been made read-only. If this is the case, you will see a message like this:
XOOPS Upgrade Make Writable Error
The solution is to change the permissions. You can change permissions using FTP if you do not have more direct access. Here is an example using FileZilla:
FileZilla Change Permission
Debugging Output
You can enable extra debugging output in the logger by adding a debug parameter to the URL used to launch the Upgrade: