State Locking

If supported by your backend, Terraform will lock your state for all operations that could write state. This prevents others from acquiring the lock and potentially corrupting your state.

State locking happens automatically on all operations that could write state. You do not see any message that it happens. If state locking fails, Terraform does not continue. You can disable state locking for most commands with the -lock=false flag, but we do not recommend it.

If acquiring the lock takes longer than expected, Terraform outputs a status message. If Terraform does not output a message, state locking is still occurring if your backend supports it.

Not all backends support locking. The documentation for each backend includes details on whether it supports locking or not.

Force Unlock

Terraform has a force-unlock command to manually unlock the state if unlocking failed.

Be very careful with this command. If you unlock the state when someone else is holding the lock it could cause multiple writers. Force unlock should only be used to unlock your own lock in the situation where automatic unlocking failed.

To protect you, the force-unlock command requires a unique lock ID. Terraform will output this lock ID if unlocking fails. This lock ID acts as a nonce, ensuring that locks and unlocks target the correct lock.