Fix S3 Upload in AWS: Multipart Failed Solution (2026)
How to Fix “S3 Upload” in AWS (2026 Guide) 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 Go to AWS S3 > Bucket Settings > Properties > Multipart upload. Toggle Multipart upload to Enabled and set the Part size to 100MB. 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: ...