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Posted: **Mon Jun 01, 2026 12:18 pm**

Demonstration: https://www.twitch.tv/zaspar_/clip/Obli ... KA-0BI4wV-

Expectation: should be only belts placed here, no underground.

Replay: https://drive.google.com/file/d/1uE9N38 ... sp=sharing

Posted: **Sun Jun 21, 2026 5:00 pm**

Hi, i tested this and i managed to reproduce this bug everytime you to have a belt placed horizontaly (it works vertically too), place one or less than 5 belt spaced by one tile. facing or not the first one but vertically. Then start placing and dragging your cursor from the futher belt till you are on the belt placed horizontaly then go backward.

Your cursor MUST go hover the horizontal belt or else it works like a charm

here is a video of the way to reproduce the bug

Underground_Belt_Bug.mp4: (33.45 MiB) Downloaded 36 times

Factorio Forums

[Kovarex] [2.0.77] Smart belt dragging causes an underground to be placed over empty space

[Kovarex] [2.0.77] Smart belt dragging causes an underground to be placed over empty space

Re: [2.0.77] Smart belt dragging causes an underground to be placed over empty space