Every reason, every field.

What each failure reason means, what an entry actually contains once it is written, and the full list of DLQ methods with their embedded and TCP behaviour.

Reference

Why jobs end up in the DLQ

Reason	Description
`explicit_fail`	A retryable processor failure in the attempt history
`max_attempts_exceeded`	A normal processor failure exhausted the job’s attempts
`timeout`	A processing timeout; retained on retry attempts and terminal timeout entries
`stalled`	Job stopped sending heartbeats (worker likely crashed)
`ttl_expired`	Reserved category; current waiting-job TTL expiry removes the job instead of creating a DLQ entry
`worker_lost`	Reserved category; current disconnect/lock recovery is classified as `stalled`
`unknown`	Fallback for unclassified failures

The entry’s reason is the terminal cause. Its attempts array preserves the cause of every failed attempt, so a timeout followed by a normal processor failure is represented as [timeout, max_attempts_exceeded], while two consecutive timeouts remain [timeout, timeout].

Entry structure

interface DlqEntry<T> {
  job: Job<T>;                    // The failed job
  enteredAt: number;              // When first moved to DLQ
  reason: FailureReason;          // Why it failed
  error: string | null;           // Error message
  attempts: AttemptRecord[];      // Full attempt history
  retryCount: number;             // Times retried from DLQ
  lastRetryAt: number | null;     // Last DLQ retry time
  nextRetryAt: number | null;     // Next scheduled auto-retry
  expiresAt: number | null;       // When entry expires
}

Each AttemptRecord carries the attempt number, start and failure timestamps, failure reason, error message, and duration in ms.

Where to go next


DLQ Operations from the Queue Object	The same operations from an existing Queue instance
Dead Letter Queue	What the DLQ is, and a first look at what failed
DLQ Operations	Filter, retry selectively, check health, purge
Automatic DLQ Retry with Backoff	Let bunqueue re-queue dead entries on a backoff
DLQ Configuration	autoRetry, maxAge, maxEntries and the defaults