Factorio Forums

1. What did I do?

Have a saved game, and then add or remove any mod that adds technologies.

Steps:
1) Load save, note that the steam technology is partially completed
2) Add any mod that adds at least 1 technology (or remove a mod with a technology, but this save has no mods enabled)
3) Load Save

2. What happened?

The steam power technology is now 0% complete, presumably every single trigger tech was reset to 0% complete.

3. What did I expect to happen instead?

The technology retains its previous completion state, (though I'd understand if newly added trigger technologies started from 0 as you weren't working towards them before.)

4. Does it happen always, once, or sometimes?

Always.


This isn't a big deal for the default technologies, but any mods that require crafting dozens or hundreds or thousands of items will really be set back by this bug.

This is suspicious because we have a test that exactly this does not happen.

It seems to be consistent from my tests, and I only looked into it because there was another person who was trying to figure out why their trigger tech was so far behind their total production despite that mod being active from the beginning of their save.

This is now fixed for the next release. It turns out, one version of the reset preserved the values, and another didn't.