[2.0.77] Modded elevated rails: upgrade planner doesn't work on some arbitrary rail tracks

[snouz]

Hi, I came back to modding today and noticed a new bug from a report on my mod https://mods.factorio.com/mod/minimalist-rails.

My mod adds rails, ramps and elevated rails. The upgrade planner recognizes every section from the normal rail to be replaced by modded rails.
I have the robots, the materials, most sections are replaced correctly, but not all. Some specific elevated rails, and rail ramps, don't want to upgrade.
The exact behavior is: green arrow appears, bot takes a new rail and goes to the rail, bot arrives and removes the green arrow, rail doesn't change, bot comes back with the new rail. So like it changed it from "old" to "old". As seen on the screenshot, it's not specific shapes, it seems related to the position with ramps and pylons. Also, if I try to build a new rail or new ramp on top of the old one manually, ramps don't let me (as seen in photo 4) and rails stay the same.

06-14-2026, 19-08-47.png (181.64 KiB) Viewed 346 times

06-14-2026, 19-09-01.png (1.67 MiB) Viewed 346 times

06-14-2026, 19-07-39.png (3.44 MiB) Viewed 346 times

06-14-2026, 19-14-50.png (417.87 KiB) Viewed 346 times

[Rseding91]

Thanks for the report however I don't believe we will be changing this. Elevated rails have a lot of rules about being buildable from some-distance-to-the-nearest-support and likely this is conflicting with being able to arbitrarily remove and replace them in the elevated state (which is how upgrading works).

This is a case that was never intended during the development of elevated rails - but we never blocked the ability to order robots to do it.