在Airflow任务中调用Lambda失败的问题的解决方法为：使用boto3库进行Lambda的调用，确保在调用Lambda时提供正确的AWS账户凭证。代码示例：

import boto3

def invoke_lambda(payload):
    # Replace with your AWS account ID
    aws_account_id = '123456789012'
    # Replace with your AWS region
    aws_region = 'us-west-2'
    # Replace with your Lambda function name
    function_name = 'my-first-lambda-function'
    # Create a Lambda client using boto3
    client = boto3.client('lambda', region_name=aws_region)
    # Invoke the Lambda function
    response = client.invoke(
        FunctionName=function_name,
        InvocationType='RequestResponse',
        LogType='Tail',
        Payload=payload.encode('utf-8'),
        Qualifier=f'arn:aws:lambda:{aws_region}:{aws_account_id}:$LATEST'
    )
    # Return the Lambda function response
    return response['Payload'].read()

注意：在使用此代码示例之前，请确保已经安装了boto3库，并替换代码中的AWS账户ID、AWS区域和Lambda函数名称为实际的值。