[2.1.13] Underground belts on top of normal belt no longer auto rotate

[Mnemonic]

08-05-2026, 07-40-21.png (453.11 KiB) Viewed 963 times

When placing an underground on top of a normal belt, the underground doesn't rotate and become an upderground. It works fine if not on top of an existing belt.

[riking]

The change log lists a change here, but that change was only supposed to apply to fast replace on an existing underground with an exit already placed. It appears that the no rotation was instead applied to all fast replace.

EDIT: In particular, fast replace on an underground that exist but does not have a matching pair should also not suppress rotation.

[koelkastdeur16]

Same issue when placing on an existing ghost belt

[boskid]

So far this report looks like full of observations that behavior was changed but no arguments saying why the changed behavior is incorrect which leaves me no choice to throw this to Not a bug.

[Bilka]

It breaks the third gif in https://www.factorio.com/blog/post/fff-206, this is clearly a bug.

[Trainzack]

The same behavior is also occurring when replacing pipes with pipe to ground.

[Bilka]

Indeed, and that is shown off in https://factorio.com/blog/post/fff-240 so also a bug that it is now broken.

[Mnemonic]

So far this report looks like full of observations that behavior was changed but no arguments saying why the changed behavior is incorrect which leaves me no choice to throw this to Not a bug.

While I'm not the decider of what shall be a bug, I will say that having different behavior when placing an underground on the empty ground and an underground on an existing belt just seems confusing. It also eliminates any value in replacing belts with undergrounds automatically.

[pomvoid]

I came (and registered) to report the same thing after noticing it right away.
It appears to have only started after my game updated today, and I would argue as to it being a bug owing to it seemingly breaking previously established functionality with no mention in any patch notes or so forth.

(Not to mention it's been quite frustrating to no longer have that functionality so abruptly.)

[ThatChapThere]

I understand the argument as to why this isn't a bug but I think this is pretty unambiguously a decrease in quality of life compared to previous versions. I can't imagine many situations where you replace a belt with an underground where you don't then need a rotated underground and can imagine even fewer where a non rotated underground is needed.

[rimbas]

Placing an underground belt exit picks up unneeded normal transport belts after creating the section and this behavior breaks that workflow.

[burninghey]

Broke in 2.1.13 and was fine before so how would this be no bug. I'm fast replacing belts with undergrounds all the time and it just stopped working in remote view.

08-06-2026, 05-08-15.png (68.59 KiB) Viewed 414 times

[EvilPLa]

Just tested this and it feels definitly like a bug.

When you don't release the mouse button and start draggin the underground along the belt it rotates direction as expected.

I'm personally a "click and release" preferer on this, it gives more control of the action

[boskid]

Ok, fix for 116547 is now reverted (for 2.1.14) which fixes this bug report. This time there is a test covering this behavior so it does not break again in the future.