@PamelaPalacios I had the exact same problem with the Coorinberg cottage I recently uploaded. Three whole bedrooms upstairs. I removed roof (not the problem), replaced walls, made little x-shaped walls (which worked for most of the area in the rooms), then, remembering Sims 1, added wall downstairs (didn't help), finally replaced rooms because there was a 2x1 area in front of two of the doors to a bath and bedroom that my sims could not get to (didn't work). I "solved" the problem by extending one room entry 1-tile out and just making it a diagonal wall over the remaining 1-tile area they can't walk in. I just assumed the game hated me personally.
@crinrict I have one that I uploaded that I haven't taken down yet. My earlier version of Coorinberg Cottage. Interestingly, the cat could get in and out of the rooms, but not my sims.
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@crinrictToo late. Already uploaded to gallery. And I just checked and The Summer Home already in my gallery also has this problem in the upstairs hall.
Also, I've been experimenting on my poor Sim, and the issue seems to be fences. Walls are fine, but as soon as I replace them with fences, he can't get there from here.
