Removal of quality research breaks other mods dependencies on the tech; make it cheap instead maybe?

Can you tell which mod(s) doesn't work? It depends on what they want to do with it. I have a draft for a post in suggestions where one of the points was to move tech removal down the data stage to get better mod compatibility, for example from data to data-update + add mods to optional dependencies, so it'll iteract with tech tree after them. and if other mods add effects beside quality-unlock to the tech, then it'll remain, while quailty-unlock effects still will be moved to the specified in settings tech

Removal of quality research breaks other mods dependencies on the tech; make it cheap instead maybe?

This is intentional. The mod however only deletes dependencies on technologies with ONLY quality unlocks, and all technologies depending on it depend on the things it depends on instead. The progression tree is not completely broken, but instead qualities are simply moved back to a previous technology.

The progression tree is not completely broken, but instead qualities are simply moved back to a previous technology.

it would work that way if other mods changed legendary-quality before your mod attempted to move quailty-unlocks. but that's not the case most of the time - the mod updates techs during data.lua, while many quality related mods interact with tech in data-update.lua, so they attempt to access already deleted tech. That's why i wanted to suggest

to move tech removal down the data stage to get better mod compatibility, for example from data to data-update + add mods to optional dependencies, so it'll iteract with tech tree after them, even if they access techs during data-update

It was specifically Fulgora Expanded, I tested this with another mod that removed the research and the same issue appeared

Ah, so it is an issue. Sorry for mis-interpreting your original version. I'll work on it when possible.

well, fulgora expanded changes epic-quality in data-final-fixes. so my suggestions won't help. in that case keeping quality techs even without effects should help - like adding option not to remove techs.
Do you have git or something like that, where i can post/suggest some changes?

I think this issue is also accruing with the mod prismatic quality

This only occurs when mods depend on the epic-quality and legendary-quality technologies (known to you as Epic Quality and Legendary Quality) before my mod loads. This makes it somewhat inconsistent which mods are incompatible for this reason - and as such, I will keep this thread open for people to tell me which mods are incompatible - so I can notify the developers of those mods in a developer-friendly way which will tell them exactly how to fix the issue.

I will also move certain modifications of existing prototypes into the data-updates.lua file so that incompatibilities with some mods don't occur anymore.

Also, hooray! 2K downloads!

Mod SpaceAgeWithoutSpace does all of its changes in data_final_fixes, and as such, breaks with this mod loaded. https://mods.factorio.com/mod/SpaceAgeWithoutSpace

I believe Quality Plus and Unlimited Quality are both effected by a change In this mod after 1.2.3 or 1.2.4. I don't recall which was the last version where all three worked together. The errors both are included below. I am not currently playing with either but it did effect a previous save when I tried loading it.

Failed to load mods: QualityPlus/data.lua:200: attempt to index local 'epicTech' (a nil value)
stack traceback:
QualityPlus/data.lua:200: in main chunk

Failed to load mods: unlimited-quality/data-updates.lua:47: attempt to index field 'legendary-quality' (a nil value)
stack traceback:
unlimited-quality/data-updates.lua:47: in main chunk