# Diagnosing a stale Terraform state lock
## Symptom
`Error: Error acquiring the state lock`, and the Lock Info `Who`/`Created` point at a process that should be finished: a CI job that ended, a laptop that rebooted, a terminal that was closed.
## Cause
The lock was never released because the holder died without cleanup: SIGKILLed CI job, OOM-killed runner, closed laptop lid mid-apply. The lock record in DynamoDB (or the S3 lockfile) outlives the process.
## Confirmation
1. Read the Lock Info ID. Note the exact lock ID string.
2. Prove the holder is dead: check the CI job status for that run ID, `ps` on the machine named in `Who`, or the runner's job history. A finished/failed job with no running terraform process means stale.
3. Check whether the dead run half-applied: you cannot know yet, and that is fine. Do not touch state until the lock is cleared and you can plan.
## Fix
1. `terraform force-unlock [lock-id]` with the exact ID from the error. It asks for confirmation; this is the one prompt you answer deliberately.
2. Immediately run `terraform plan` (not apply). Read the whole plan.
## Verification
1. The plan tells you what the dead run did: creates/updates that already happened show as no-change or as drift to reconcile; unfinished work shows as pending changes.
2. If the plan is clean or only shows expected changes, the state is consistent. Proceed normally.
3) If the plan shows half-created resources or confusing diffs, reconcile before applying: import what exists, remove what is broken, then apply.
4. Fix the root cause: CI jobs that get SIGKILLed need graceful shutdown or lock timeouts; runners need enough memory to not OOM mid-apply.