Game suddenly crashing on one specific mod scenario

I’ve got a mod that’s been in progress for about 7 months; the first campaign has been up for about 3.5, but suddenly one specific scenario is causing a crash, despite not changing at all. It crashes at T= 00:00:00, before anything loads, which tells me it’s an issue with the way the game is handling it, not the scenario itself.

I’ve tried to fix it, but the crash logs are useless, they just give a meaningless 404 error with a ExtensionDoExternalCallEvent failure, which means nothing to me because there are no external events.

Has anyone dealt with this before, and if so, why does it do this suddenly?

Here’s the crash log, maybe someone who speaks computers better can get something out of it.

2024.11.25-15.15.40.txt (17.1 KB)