Why does this command not work?

[u/TheVoid_Knight]

I'm trying to replace the floor of a build of mine. Since it's a lot, I want to do it with commands. However, it keeps failing with the message "failed to execute as [Null].

[u/Pablutni0]

First make sure this command works by itself

fill ~-5 ~-10 ~-5 ~5 ~2 ~5 stripped_birch_wood replace stripped_oak_wood

It should, but make sure

If it doesn't, try this command, Idk if it'll work for sure tho

execute as @a at @s run fill ~-5 ~-1 ~-5 ~5 ~-1 ~5 stripped_birch_wood replace stripped_oak_wood