This is the #1 culprit. When the Biotech or Anomaly DLCs were released, Ludeon Studios changed how Site spawning works. Mods that add custom factions (e.g., Empire , Vanilla Factions Expanded - Mechanoids ) or custom biomes ( Alpha Biomes , Regrowth ) sometimes hardcoded site labels. If a mod author used an old patch to generate sites, but forgot to update the label logic for the SitePartDef , the game throws this error because it finds the physical site (the map tiles) but cannot find the label for the "New" instance.
If you remove a mod that adds custom factions, biomes, or world locations mid-game, the save file continues to call for that missing mod's data. rimworld err site label detected new
(often related to custom factions or quest-adding mods) or outdated translation files. This is the #1 culprit
This specific layout structure indicates several distinct software failure types: If a mod author used an old patch