Quick answer: Godot 4 export failing with template-version-mismatch error after engine upgrade? Templates aren't auto-updated - download new templates matching the engine version.

Updated editor from 4.2 to 4.3. Export fails: template version 4.2.x does not match engine 4.3.x.

Reinstall templates

Editor > Manage Export Templates > Download. Pulls templates matching the current engine version.

Or specify custom path

Export preset > Custom Debug/Release Template. Point to a specific build if you need a non-default template.

Pin both versions in CI

Build script downloads engine and templates from the same release URL. Mismatch becomes structurally impossible.

“Templates are version-locked to the engine that built them. Mixing them is rejected.”

Document the version pinning in your CI README. New contributors will skip the template install step and burn a half-day before realizing the cause.