使用AWS Lambda中的死信队列来保存未能被处理的消息并解决问题。创建一个SQS队列作为Lambda函数的死信队列，然后将其配置成函数的目标，当函数无法处理消息时，消息将被推送到死信队列。以下是一个代码示例：

import boto3
import json

def lambda_handler(event, context):

    # Connect to SQS
    sqs = boto3.resource('sqs')
    queue = sqs.get_queue_by_name(QueueName='sqs_queue_name')
    dead_letter_queue_arn = 'arn:aws:sqs:{region}:{account_id}:lambda_dead_letter_queue_name'
    
    # Create Lambda dead letter queue if it doesn't exist
    try:
        response = sqs.create_queue(QueueName='lambda_dead_letter_queue_name')
        dead_letter_queue_arn = response.attributes.get('QueueArn')
    except:
        dead_letter_queue_arn = 'arn:aws:sqs:{region}:{account_id}:lambda_dead_letter_queue_name'
    
    # Process messages from SQS queue
    for message in queue.receive_messages(MessageAttributeNames=['All']):
        try:
            # Process message
            print(message.body)
        except:
            # Send message to dead letter queue on processing error
            dead_letter_queue = sqs.Queue(dead_letter_queue_arn)
            response = dead_letter_queue.send_message(MessageBody=message.body)
            print("Message sent to dead letter queue: ",response['MessageId'])