⁉️ Can a player open a crate with a full inventory?

#Answer

Only with the Crate Claim add-on installed.

Without it, a player whose inventory is full is refused before anything happens. They are told their inventory is full and no key is taken, which is deliberate so a reward is never lost to a missing slot.

With Crate Claim installed the crate opens normally and anything that does not fit is stored for the player to collect with /crate claim.

The same applies to keys, crates and rewards handed out by command, which are dropped at the player's feet without the add-on and stored with it.