👀 Views: 82 💬 Answers: 1 📅 Created: 2025-06-10

AWS Lambda boto3 S3 multipart-upload Python

I recently switched to I'm migrating some code and I'm optimizing some code but I'm collaborating on a project where I'm working with an scenario with my AWS Lambda function that uses the `boto3` library to download a file from S3. I've implemented a multipart upload process, and while the upload itself works fine, I get an behavior when trying to download the file afterward. The behavior message reads: `botocore.exceptions.ClientError: An behavior occurred (404) when calling the HeadObject operation: Not Found`. Here's the relevant snippet of my Lambda function: ```python import boto3 from botocore.exceptions import ClientError def lambda_handler(event, context): s3 = boto3.client('s3') bucket_name = 'my-bucket' object_key = 'uploads/my-large-file.zip' # Attempt to download the file try: s3.download_file(bucket_name, object_key, '/tmp/my-large-file.zip') print('File downloaded successfully') except ClientError as e: print(f'behavior: {e}') ``` I've double-checked the bucket name and the object key, and they seem correct. I verified that the file exists in the S3 console under the specified path. I'm also using the appropriate IAM role for the Lambda function with permissions to access S3, including `s3:GetObject`, but still no luck. Could there be something I'm missing about the state of the S3 object after the multipart upload? I tried adding a delay before attempting the download, thinking there might be a propagation delay, but the question continues. Any insights would be appreciated. I'm working on a web app that needs to handle this. What's the best practice here? The project is a REST API built with Python. Is this even possible? Hoping someone can shed some light on this. Any help would be greatly appreciated! I've been using Python for about a year now. I'd really appreciate any guidance on this. I'm working in a Windows 11 environment. Could this be a known issue?