I'm installing TS3 from my old discs I found. I have basegame + all expansions. I can get mods from other sources to work (like Lazy Duchess' smoothness patch). I used Nexus Mods GPU addon to get it to recognize my modern graphics card.

But cannot install MasterController, ErrorTrap, etc.

If I put the mods in, the game either crashes after getting to the loading screen with the green bar (with Master Controller.) Or I get an error message about an 'unauthorised core mod' (with ErrorTrap). If I take them out and load without them, no crash.

What am I doing wrong? Is it because I'm installing from a disc? I've tried to follow directions, install packages into Mods folder, delete CASpartcache, compositorcache etc. with each new mod. I am essentially working from a clean slate so I don't understand what's wrong. (Short of a clean Windows install which I would prefer not to...)

Try following this advice and update the game via SuperPatcher (or via Origin/EA app if you like).

Thanks Knight! I've just updated with SuperPatcher (Didn't realise that existed, so I thought when it said it had updated in the launcher, that it had fully updated..... thanks EA!)

Gone into my game and it appears NRAAS is now working and the game is playing, however, I still get a warning message about 'unauthorised core mod'. Not sure how to get this to go away.

Most likely, you are getting this warning because you have installed ErrorTrap, which is the core mod. Have you installed this version?

Anyway, you can simply ignore this warning.