What causes a companion mod crash when entering new cells?

[NatalieSP]

I’m trying to get a custom companion mod to work, but it keeps crashing whenever they try to enter a new cell with me. I’ve checked that my other mods are compatible and the load order seems right, so I’m not sure what’s causing the persistent script failure.

[Jason37]

I had that exact crash. I made a clean test profile with only the companion mod on, and it still crashed when entering a new cell. That ruled out load order as the issue.

[RobertVG]

Turns out updating the mod to the latest version fixed it for me, or at least reduced the frequency—sometimes conflicts with other mods that touch interiors.

[Jacob7]

Sometimes the log points to a missing reference or an AI package call; I skimmed a crash log and saw something about a function not loaded.

[Mason82]

I kept thinking the problem was the cell data itself, not the mod, and drifted off to check save file size and memory usage, but that went nowhere.