I developed a method for an user changes its password. I'm using UserDB and the method changes the password in the database.

After the change is made the user is warned his/her login is invalid and he/she must login again with the new passord.

Is there anyway to avoid that?

If you're using cookie-based authentication you could set the cookie in the same form that accepts the new password and sets it in the database. I believe the name of the variable is __ac__password but I'm not sure. View Source in the Zope management UI inside a UserDB user edit screen and you'll see the password. --Rob