https://github.com/MagmaMcFry/Factorissimo2/issues/27

Apparently your mod now merges various tile prototypes to landfill until the tile prototype number is below 255. This causes "Unknown tile name" runtime errors whenever one of these deleted tile types is placed using some other mod's control script, because the script relies on that particular tile type still existing.

I assume you're giving vanilla tiles exemption from being deleted. Could you please also do that for Factorissimo2's tiles, since they're all being script-placed? You can find the tile names here:

https://github.com/MagmaMcFry/Factorissimo2/blob/master/prototypes/tile.lua

If people get errors like that they're supposed to uninstall mods that put them over the limit.
I've added Factorissimo2 tiles to a higher priority list so they should be preserved over other cosmetic ones.
If you add more tiles you can make them a priority with:

alien_biomes_priority_tiles = alien_biomes_priority_tiles or {}
table.insert(alien_biomes_priority_tiles, "my-tile-name")

Ah, thanks for the info.

"If people get errors like that they're supposed to uninstall mods that put them over the limit."

after reading the above, i understand it, but which "normal" user is supposed to know in the first place that there is such a limit of 255 tiles, and that the error message of another mod "tile does not exist" is caused by this effect and by your mod removing tiles (and not typing errors etc in the other mod), and how am i supposed to know which mods add how many tiles (that they later need to refer to) so that i can remove or adjust those mods that have the largest effect (the most new tiles) ?

I get this effect when using AlienBiomes, AsphaltRoads, PavementDriveAssist, Dectorio and quite a few other mods at the same time, where i have no idea whether and how many tiles they add and whether they need to refer to such (non-existing) tiles. I enjoy driving on autopilot through beautiful landscapes and would like to continue to do so ...

edit: since i wrote the above, i went to the forums and tried some combinations of mods. it seems that using the HR textures might help for some people since that changes the load order (instead of applying the final-fixes almost first among all mods, they are applied almost last when using also the HR textures). for some details go to the forums thread ...