Whenever I try to meditate on the Whitcher 3 it says "you cannot do this now". Any help? I'm not on a horse or anything I'm just in the city of Novigrad and I can't meditate.
Meditating inside cities is allowed, but some missions stops you from meditating. If you're not actively on a mission, it's a bug. Try to save and reload. If that fails, restart the game. If that fails as well, you probably need to load an older save.
Go outside the city of Novigrad and try to meditate then.