how to fix Webmin after upgrading to Ubuntu 11.04
After upgrading my Ubuntu box to 11.04 (Natty Narwhal), I found I couldn't log in to Webmin anymore. You may have had this same problem.
If you were able to use Webmin before, and now, suddenly, you can't, then perhaps you have lost Webmin privileges. Fortunately, if you still have sudo privileges, you can probably get your Webmin privileges back simply by adding yourself as a Webmin user.
To do this, try the following:
First, reset the root password:
sudo passwd root
Next, sign into Webmin as root, using the new password you created.
Expand the Webmin menu and click on Webmin Users.
Click on Create a new Webmin user.
Enter your username into the Username field and fill out the rest of the form with the settings you prefer. Be sure to grant yourself access to all of the appropriate Webmin modules by selecting the check boxes under Available Webmin modules.
Complete the operation by pressing Create.
Log out of Webmin.
Try logging back into Webmin again, this time by using your own username, which you just enabled.
If all went well, then you should restore your root password to its disabled state:
sudo passwd -l root