> ## Documentation Index
> Fetch the complete documentation index at: https://mintlify.com/taskforcesh/bullmq/llms.txt
> Use this file to discover all available pages before exploring further.

# ErrorCode

> Enum of error codes returned by BullMQ Lua scripts

## Overview

The ErrorCode enum contains error codes that can be returned by BullMQ's Lua scripts when operations fail.

## Enum

```typescript theme={null}
enum ErrorCode {
  JobNotExist = -1,
  JobLockNotExist = -2,
  JobNotInState = -3,
  JobPendingChildren = -4,
  ParentJobNotExist = -5,
  JobLockMismatch = -6,
  ParentJobCannotBeReplaced = -7,
  JobBelongsToJobScheduler = -8,
  JobHasFailedChildren = -9,
  SchedulerJobIdCollision = -10,
  SchedulerJobSlotsBusy = -11,
}
```

## Error Codes

### JobNotExist

<ParamField path="JobNotExist" type="-1">
  The specified job does not exist in Redis
</ParamField>

This error occurs when trying to operate on a job that has been removed or never existed.

```typescript theme={null}
// Example: Trying to get a non-existent job
const job = await queue.getJob('non-existent-id');
// job will be undefined
```

### JobLockNotExist

<ParamField path="JobLockNotExist" type="-2">
  The job's lock does not exist
</ParamField>

This error indicates that the job is not locked, which can happen if:

* The lock expired
* The job was never locked
* Another worker stole the lock

### JobNotInState

<ParamField path="JobNotInState" type="-3">
  The job is not in the expected state for the requested operation
</ParamField>

For example, trying to promote a job that's not in the delayed state:

```typescript theme={null}
// This will fail if job is not delayed
await job.promote();
```

### JobPendingChildren

<ParamField path="JobPendingChildren" type="-4">
  The job still has pending children and cannot be processed
</ParamField>

This occurs when trying to move a parent job to active while it still has unfinished children.

### ParentJobNotExist

<ParamField path="ParentJobNotExist" type="-5">
  The parent job specified does not exist
</ParamField>

Occurs when creating a child job with a non-existent parent:

```typescript theme={null}
await queue.add('child', { data }, {
  parent: {
    id: 'non-existent-parent',
    queue: 'bull:parentQueue',
  },
});
```

### JobLockMismatch

<ParamField path="JobLockMismatch" type="-6">
  The provided lock token doesn't match the job's current lock
</ParamField>

This prevents one worker from modifying a job locked by another worker.

### ParentJobCannotBeReplaced

<ParamField path="ParentJobCannotBeReplaced" type="-7">
  The parent job cannot be replaced while it has children
</ParamField>

Occurs when trying to replace a job that has child dependencies.

### JobBelongsToJobScheduler

<ParamField path="JobBelongsToJobScheduler" type="-8">
  The job belongs to a job scheduler and cannot be modified directly
</ParamField>

Jobs created by job schedulers (repeatable jobs) cannot be modified directly.

### JobHasFailedChildren

<ParamField path="JobHasFailedChildren" type="-9">
  The job cannot proceed because it has failed children
</ParamField>

This error occurs when a parent job's children have failed and the parent cannot continue.

### SchedulerJobIdCollision

<ParamField path="SchedulerJobIdCollision" type="-10">
  A job scheduler with this ID already exists
</ParamField>

Occurs when trying to create a job scheduler with an ID that's already in use.

### SchedulerJobSlotsBusy

<ParamField path="SchedulerJobSlotsBusy" type="-11">
  The job scheduler's time slots are busy
</ParamField>

This can occur when the scheduler is trying to create jobs but the slots are already occupied.

## Usage

These error codes are typically returned by internal Lua scripts and converted to JavaScript errors. You generally won't use these directly, but they may appear in error messages:

```typescript theme={null}
import { Job } from 'bullmq';

try {
  await job.promote();
} catch (error) {
  console.error('Failed to promote job:', error.message);
  // Error message may reference error codes
}
```

## Handling Script Errors

When BullMQ operations fail, the errors usually include descriptive messages:

```typescript theme={null}
import { Queue } from 'bullmq';

const queue = new Queue('myQueue');

try {
  await queue.remove('job-id');
} catch (error) {
  if (error.message.includes('locked')) {
    console.log('Job is locked by another worker');
  } else if (error.message.includes('not exist')) {
    console.log('Job does not exist');
  }
}
```

## Related

* [UnrecoverableError](/api/errors/unrecoverable-error) - Error to fail jobs immediately
* [RateLimitError](/api/errors/rate-limit-error) - Error for rate limiting
* [Job](/api/job) - Job class that may encounter these errors