Sorry for the inconvenience.  Known Navigation header breakage, its being "rebuilt."
There may be other unforeseen breakage primarily in the handbook portion of the wiki.
The Table Of Contents section of each "PC-BSD® Users Handbook" page may be the best workaround.

Translations:Pc-updatemanager/9.2/18/en

From PC-BSD Wiki
Jump to: navigation, search

Once the downloads are finished, a pop-up message will indicate that the system is now ready to reboot in order to finish the upgrade. PC-BSD® will not automatically reboot the system, giving you the opportunity to close any applications that you have open before you reboot the system yourself.

Translations:Handbook translating/common/12 It is very important that once you reboot, you do not interrupt the upgrade process. This process may take up to 30 minutes, so plan your reboot for a time when you do not need immediate access to your system.
Personal tools

Variants
Actions
Navigation
Toolbox