这个问题通常是由于ARN不正确或S3事件不正确地发布到Lambda函数引起的。下面是一个代码示例，使用Lambda函数的ARN订阅S3事件：

import boto3
client = boto3.client('s3')
 
def lambda_handler(event, context):
    # Get the bucket name and object key from the S3 event
    bucket_name = event['Records'][0]['s3']['bucket']['name']
    object_key = event['Records'][0]['s3']['object']['key']
    
    # Get the ARN for the Lambda function you want to invoke
    function_arn = 'arn:aws:lambda:us-east-1:123456789012:function:my-function'
    
    # Configure the invocation request with the payload required for the function
    invocation_payload = {
        'bucket_name': bucket_name,
        'object_key': object_key
    }
 
    # Invoke the Lambda function specified by the ARN
    response = client.invoke(
        FunctionName=function_arn,
        Payload=json.dumps(invocation_payload)
    )
    
    # Log the response from the invoked function
    print(response['Payload'].read())

确保在上面的代码示例中将function_arn替换为你要调用的Lambda函数的ARN。

如果这个解决方法不能帮助你解决问题，可以进一步检查ARN, Lambda函数和S3事件等信息是否正确。