2
You should upgrade directly to
XOOPS 2.4.1. See the upgrade instructions there.
Of course, you might need to update all the modules as well to newer versions. So before you go with the upgrade, if you still have access to Admin, you might first "deactivate" your modules (don't uninstall them, just deactivate), then upgrade XOOPS, and then activate your modules one by one, to make sure that they work.
If any of them doesn't work, you will need to update them to a newer version, if such exist, or look for replacement.