Hello,

I am trying to replace a vanilla texture via ARRP.
But if I add a texture like RESOURCE_PACK.addTexture(new Identifier("minecraft", "/gui/options_background"), image);,
it changes nothing.

This is likely because of how you're registering the pack

I am registering the pack like this: RuntimeResourcePack.create(MODID + ":resource");. How to register the pack, so I can replace vanilla textures?

Ohh sry. This is how i am register the pack: RRPCallback.AFTER_VANILLA.register(a -> a.add(RESOURCE_PACK));

use BEFORE_VANILLA it says it in the documentation

@Devan-Kerman tried this already and now again, it doesnt work...

I'll take a look when I get back

ensure your path is correct, try dumping resources with RuntimeResourcePack#dump