3
Sometimes, if I've previously cut ' paste a password, the browser has 'saved' it for next time but with a space at the end. I guess XOOPS recognised the space as another character and refused it. I'm not saying that this is what has happened in your case but it's worth checking.
If this doesn't help, you might want to manually type it in on the various pages throughout XOOPS where asked, until such time as the issue is resolved.