i have encountered this error after updating the mod: https://cdn.discordapp.com/attachments/812703756293505075/1235314967255973938/factorio_IGZYkf9go6.png?ex=6633ec37&is=66329ab7&hm=e02b83460504a87819b19a938376853fea061ce4211db70044c000f1119b848e&

Can you let me know what mods you have installed? This doesn't happen with just the mod on its own for some reason. It should be compatible with other mods as much as possible, so this is still a bug, I just need to figure out what other mods are interacting badly.

If you have tons of mods, just let me know which ones might touch the "upgrade lines". Essentially, assembling machines have a next_upgrade property that tells the game that assembling machine 1's are upgraded to assembling machine 2's. Anything that adds to or modifies this next_upgrade may be interacting badly with the mod.

Until then, you can open the mod in an otherwise vanilla configuration, disable the "Preserve upgrade lines" setting near the top, then restart with your chosen set of mods. This should allow the game to load until I fix this, albeit without one of the new features that was added.

I can compile a list of all mods i have enabled in the save but i dont see a reason why any of the mods should be touching the Next_upgrade field of assembling machines as i havent added any mods which declare that assembling machine changes are part of there content or that they do anything like adding new ones where this would make sense.

If you could do that, it would be great. I cannot fix the issue without being able to reproduce it, unfortunately. Other mods can often do things in unexpected ways, so I still have to investigate them. I can also test with my mod alone if I'm able to get the seed and other startup settings for my mod. Hopefully this isn't asking too much.

Thanks again for the report. Without people like you I'd never catch these bugs!

im going to do you one better and upload a copy of the save, that way you should be able to get all the mods, all the settings from all the mods.
maybe you can also see regarding the other thing i reported about negative crafting speed since it kept happening, seems like when it started doing that and after it got unlocked from the cap the randomizer progressed far enough to reach a streak of mostly negative numbers.
dont know if it will help for that but i felt bad that i wasnt able to provide more then the seed then so since it keeps happening now, i can give you the save and most likely within 5 speed changes it will at least once be negative.
https://drive.google.com/drive/folders/18Fxvpra0UAh-USNEIRPqA9v5UjlRklJx?usp=sharing

So sorry it's been negative again! There are commands to increase crafting speed back up so you don't have to play a forced lazy bastard run in case you need. Also thanks so much I'll look into it.