This occurs if you uninstall a version Gamma 3+, re-install Gamma 2-, and then attempt to upgrade; or if you uninstall a version < Gamma 3, reinstall a version > Gamma 3, uninstall that version, re-install > Gamma 3 with vBulletin CMS disabled, enable vBulletin CMS, attempt to upgrade VaultWiki. There may be other ways to duplicate this, but those are 2 ways I was able to do it.
The second way is already patched if the newest installation was Gamma 5, but some entries were not removed during the uninstall script < Gamma 5, because it was expected that vBulletin removes such entries automatically. However, some users are on earlier versions of vBulletin that don't, the vBulletin bug might still be unresolved, or they use APM to uninstall their products which also doesn't.
You will have to manually execute the following MySQL query before you can continue:
Code:
DELETE FROM vb_blocktype WHERE name = 'vwsidebar'
Even though it is not possible for this to occur if a fresh installation is >= Gamma 5 or Gamma 5 was the uninstalled version, I have updated the uninstall script for the next release for completeness's sake, in case someone uninstalls Gamma 6 and then attempts to install Gamma 3 afterwards.