Update to 3.3 is not succsesfull

I've updated Pi-Hole but now the GUI is still 3.2.1 while the rest is updated.
I've followed some steps I've found: Updated to v3.3; web UI thinks CORE still at v3.2.1 - #20 by DanSchaper
When I run git checkout tags/v3.3, it gives: Pi_error
It seems to be related to permissions.
Any sugestions?

sudo git fetch --tags


OK. Dan, that did the trick.
Many thanks.