Re: Can't place stairs against ground floor walls

@ShrubBotExe 

I tested this and found no problem with stair placement.  I don't get the error you are getting.  When I try to place a stair in the position shown in your pic, I do get an error, but not the same one you show.  I get "Can't intersect with walls".  Moving the stair further down the wall lets it place as it should without an error message.

So, idk what exactly you have going on.  As you said that you use mods and removed them, this could be vestige of a mod still affecting your game.  It does happen that some mods, even after removal, leave something behind.  And you said you've used platforms.  Platforms sometimes cause some weirdness even after they've been deleted at times.  There was a problem when they were added to the game that blocked the tiles they had covered after you deleted them.  It's been fixed but you might have something similar going on.

So, to hopefully to fix the issue for you, there are a couple of things you can try.

1 - repair the game.  Also delete the localthumbcache file before you start after repairing.

2 - try a new user folder.  Just rename your "The Sims 4" folder, start the game and let it create a new one.  After making and placing the sim, save and quit.  Copy your save over from the old folder to the new one.  Then see if the issue is fixed or still there.  If it is still there, then come back and we'll go from there.

Hope this helps.