Game won't start, init.lua problem

I am running TF2 from GOG. It has been working with no problems. Yesterday I received an error on startup that it cannot open res/scripts/init.lua: No such file or directory.

The load music plays, but nothing else meaningful happens.

init.lua exists in the right place.

I have no mods.

Windows security update 2026-03 Security Update (KB5079473) (26200.8037) installed between the last time it loaded, and the first time it didn't.

Screenshot attached.

stdout.txt stdout.txt and bf0858a2-c3f3-45f6-9777-ec82b4b29465_stdout.txt bf0858a2-c3f3-45f6-9777-ec82b4b29465_stdout.txt attached.

I did do a re-install of the game and it made no difference.

res/srcripts/init.lua exists and has read and execute permissions for all accounts