The Short Answer

To fix the “Multipart Failed” error during S3 uploads in AWS, adjust the chunk size to optimize the upload process, ensuring that it aligns with AWS’s guidelines for multipart uploads. This typically involves setting the chunk size to between 5MB and 5GB, with a recommended size of 100MB for most use cases.

Why This Error Happens

• Reason 1: The most common cause of the “Multipart Failed” error is an incorrectly configured chunk size for multipart uploads. When the chunk size is too small or too large, it can lead to upload failures, especially for large files.
• Reason 2: An edge case cause is network instability or high latency, which can interrupt the upload process and cause the “Multipart Failed” error. This is more common in areas with poor internet connectivity or during periods of high network usage.
• Impact: Multipart Failed errors can significantly delay upload processes, leading to inefficiencies and potential data loss if not handled properly.

Step-by-Step Solutions

Method 1: The Quick Fix

1. Go to AWS S3 > Bucket Settings > Properties > Multipart upload.
2. Toggle Multipart upload to Enabled and set the Part size to 100MB.
3. Refresh the page and attempt the upload again.

Method 2: The Command Line/Advanced Fix

For more advanced users or for automating the process, you can use the AWS CLI to configure and perform multipart uploads. An example command to initiate a multipart upload with a specified part size is:

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aws s3api create-multipart-upload --bucket your-bucket-name --key your-object-key --part-size 100MB

Then, you can use the upload-part command to upload each part, and finally, complete the multipart upload with the complete-multipart-upload command.

Prevention: How to Stop This Coming Back

• Best practice configuration: Always ensure that your multipart upload settings are optimized for your specific use case. For most users, setting the part size to 100MB provides a good balance between upload speed and reliability.
• Monitoring tips: Regularly monitor your upload processes for failures and adjust your settings as necessary. AWS provides detailed metrics and logging that can help identify issues before they become critical.

If You Can’t Fix It…

[!WARNING] If AWS continues to experience issues with multipart uploads despite configuring optimal chunk sizes and following best practices, consider evaluating alternative cloud storage solutions like Google Cloud Storage or Microsoft Azure Blob Storage, which may offer more robust handling of large file uploads and multipart transfers.

FAQ

Q: Will I lose data fixing this? A: The risk of data loss when fixing the “Multipart Failed” error is minimal if you follow the steps carefully. However, it’s always a good practice to have backups of your critical data before attempting any fixes.

Q: Is this a bug in AWS? A: The “Multipart Failed” error is not a bug in AWS but rather a configuration or network issue. AWS regularly updates its services, including S3, to improve performance and reliability. Checking the AWS status dashboard and release notes can provide insights into known issues and recent changes that might affect your uploads.

📚 Continue Learning

Check out our guides on AWS and S3 Upload.