Some mods (like SkyUI, RaceMenu, or Engine Fixes) come with their own DLL files. Even if SKSE is updated, a specific plugin inside your Data/SKSE/Plugins folder might not be.
This is the solution for 90% of users. You likely have an old version of SKSE installed that doesn't match your current game version. skyrim dll plugins you have installed require a new version
If you have updated SKSE to the latest version and it matches your game version, but you still get the error, one of your specific mods is outdated. Some mods (like SkyUI, RaceMenu, or Engine Fixes)
The error message "DLL plugins you have installed require a new version of the Address Library" can occur for a number of reasons: Some mods (like SkyUI