[LiveComponent] Cannot assign null to property Symfony\UX\LiveComponent\Twig\TemplateMap::$map of type array

[tijnema]

Hi,

During deployment on our live environment we quite often get the error
Cannot assign null to property Symfony\UX\LiveComponent\Twig\TemplateMap::$map of type array

It seems to be related to a race condition with cache. Not sure how it occurs exactly, but it can easily be reproduced by deleting the live_components_twig_templates.map file from the cache folder.

[smnandre]

Do you sometimes prune / delete your cache folder ? Or even with a CachePoolClearer maybe ?

[tijnema]

We use Ansistrano for deployment. It places new version of the project in a new directory (with empty cache folder), and then switches a symlink to this new folder.

[smnandre]

Do you warm the cache before the symlink ? The other possibility would be: do you change your APP_SECRET between deployments ?

[tijnema]

APP_SECRET never changes. We currently do not warm the cache before symlink. That might just fix the issue.
The issue does remain when clearing the cache on a running instance though. I guess this piece of code could be written to work without existing cache too?

[smnandre]

Well, yes and no :)

Yes it would work to "render" a component.

But if you clear the cache (without rebuilding it) while a user is browsing a page containing live components, that would break.

Maybe we should generate this file in the "build" directory and not the "cache" one ?

[RikudouSage]

Is there at least some workaround? It happens constantly in one app I create, only in the docker container, though.

[smnandre]

Hi @RikudouSage, do you have APP_SECRET env variable configured?

[tijnema]

@RikudouSage Maybe you should warm the cache before running the app ?