# Using dead-letter queues in Amazon SQS with AWS SDK for PHP Version 3
<a name="sqs-examples-dead-letter-queues"></a>

A dead-letter queue is one that other (source) queues can target for messages that can’t be processed successfully. You can set aside and isolate these messages in the dead-letter queue to determine why their processing did not succeed. You must individually configure each source queue that sends messages to a dead-letter queue. Multiple queues can target a single dead-letter queue.

To learn more, see [Using SQS Dead Letter Queues](https://docs.aws.amazon.com/AWSSimpleQueueService/latest/SQSDeveloperGuide/sqs-dead-letter-queues.html).

The following example shows how to:
+ Enable a dead-letter queue using [SetQueueAttributes](https://docs.aws.amazon.com/aws-sdk-php/v3/api/api-sqs-2012-11-05.html#setqueueattributes).

All the example code for the AWS SDK for PHP is available [here on GitHub](https://github.com/awsdocs/aws-doc-sdk-examples/tree/main/php/example_code).

## Credentials
<a name="examplecredentials"></a>

Before running the example code, configure your AWS credentials, as described in [Authenticating with AWS using AWS SDK for PHP Version 3](credentials.md). Then import the AWS SDK for PHP, as described in [Installing the AWS SDK for PHP Version 3](getting-started_installation.md).

## Enable a dead-letter queue
<a name="enable-a-dead-letter-queue"></a>

 **Imports** 

```
require 'vendor/autoload.php';

use Aws\Exception\AwsException;
use Aws\Sqs\SqsClient;
```

 **Sample Code** 

```
$queueUrl = "QUEUE_URL";

$client = new SqsClient([
    'profile' => 'default',
    'region' => 'us-west-2',
    'version' => '2012-11-05'
]);

try {
    $result = $client->setQueueAttributes([
        'Attributes' => [
            'RedrivePolicy' => "{\"deadLetterTargetArn\":\"DEAD_LETTER_QUEUE_ARN\",\"maxReceiveCount\":\"10\"}"
        ],
        'QueueUrl' => $queueUrl // REQUIRED
    ]);
    var_dump($result);
} catch (AwsException $e) {
    // output error message if fails
    error_log($e->getMessage());
}
```