Failed to execute fill command on player

Question

There are other questions regarding this but they had other problems like wrong commands, so here goes:

I gave a command block the command

execute @a ~0 ~0 ~0 fill ~-30 ~-30 ~-30 ~30 ~30 ~30 minecraft:diamond_block 0 replace minecraft:gold_block

This should replace all gold blocks close to players with diamond blocks (just used them as a quick test that won't affect other things in nature). I was the only person on the server, activated the command block, but it said "Failed to execute [...] on player [me]" (It also doesn't replace the gold block conveniently placed next to me).

Is there anything wrong with the command?

Answer 1

For situations like this, I'd recommend running the command being executed itself (the /fill command) to see what the error is.

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The main error appears to be that you're trying to fill a quarter of a million blocks, which is more the maximum (32678) that Minecraft allows for. You could reduce your fill region:

/fill ~-15 ~-15 ~-15 ~15 ~15 ~15 minecraft:diamond_block 0 replace minecraft:gold_block

Or, if the huge area is important, split it up into multiple commands:

/fill ~0 ~0 ~0 ~30 ~30 ~30 minecraft:diamond_block 0 replace minecraft:gold_block
/fill ~0 ~0 ~0 ~-30 ~30 ~30 minecraft:diamond_block 0 replace minecraft:gold_block
etc.

(I'd suggest not running either of these on a clock)

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That should be it, but keep in mind that the command will also fail if there are no gold blocks to replace, or if you're too low-down/high-up so that the relative coordinate are selecting an area outside of the world.