Does a Server Action always invalidate the Router Cache?

[yongholeeme]

I know that Layouts are cached and reused on navigation. However in some situations, Layout cannot be persisted across routes and doesn't maintain state.

I made an example: https://reproduction-bug-weird-layout.vercel.app
https://github.com/yongholeeme/reproduction-bug-weird-layout

On general navigations, layout is cached and doens't rerendered. However in or after server action on navigation, layout isn't cached and rerendered although the server action doesn't do anything.

Screen.Recording.2025-04-10.at.11.48.21.PM.mov

I'm not sure if this is normal behavior or a bug. If it's the expected behavior, it would be helpful to know where in the official documentation I can find more information.

[321david123]

yeah, most cases server action will invalidate the cache and it will make sure you are seeing the latest data, that includes layout. you can isolate the layout so its not affected by the part where the server action occurs.
“After a Server Action is invoked, all affected routes and layout segments are revalidated and potentially re-rendered.”
docs: Server Actions and Caching

[321david123]

@321david123, thank you for your response. I couldn't find the text "After a Server Action is invoked, all affect~" in Server Actions and Caching. Could you give me a screenshot or more detailed link with hightlight in chrome?

It's basically this Revalidating Data: Revalidating the Data Cache, will in turn invalidate the Router Cache by re-rendering components on the server and caching the new render output

[yongholeeme]

@321david123 Yes if some revalidation function called in server action, then the cache would be invalidate. However in the above exaple, one server action doesn't anything and another do just redirect. I'm curious if just invoking a server action

[321david123]

@321david123 Yes if some revalidation function called in server action, then the cache would be invalidate. However in the above exaple, one server action doesn't anything and another do just redirect. I'm curious if just invoking a server action

In your layout, you use ‘force-dynamic’
So redirects and functions can cause a re-render because of that ‘force-dynamic’

You can change it to 'auto' and see if that works 👍

[yongholeeme]

Yes I used 'force-dynamic' to make the layout as Dynamic Route. It means it will skip the Full Route Cache and the Date Cache not Route Cache. I still cannot make sense just calling a server action can cause Route Cache Invalidation. Even official documentation introduce how to invalidate the Route Cache in server acion. https://nextjs.org/docs/app/building-your-application/caching#invalidation-1

[321david123]

Yes I used 'force-dynamic' to make the layout as Dynamic Route. It means it will skip the Full Route Cache and the Date Cache not Route Cache. I still cannot make sense just calling a server action can cause Route Cache Invalidation. Even official documentation introduce how to invalidate the Route Cache in server acion. https://nextjs.org/docs/app/building-your-application/caching#invalidation-1

Mmmh then it could be a bug or a bad explanation in the docs. Maybe someone else has the answer for this