I'm getting the following error from S3 when using the REST API to perform a multipart upload, uploading multiple parts in parallel.
One or more of the specified parts could not be found. The part may not have been uploaded, or the specified entity tag may not match the part's entity tag.
However, I have verified that all the parts upload correctly. I even took a wireshark trace and it shows all the parts uploading correctly. What else could cause this error?
One thing here to watch out for is that during the multipart completion, the part numbers in the completion message need to match the part numbers indicated during the upload. E.g. in a multipart completion like:
<?xml version="1.0" encoding="UTF-8"?>
<CompleteMultipartUpload>
<Part><PartNumber>1</PartNumber><ETag>"4ee5c4f1b14bbda5333072ee501fbbbb"</ETag></Part>
<Part><PartNumber>2</PartNumber><ETag>"2bb626328bc9f6e5318b78311ea7c7c8"</ETag></Part>
<Part><PartNumber>3</PartNumber><ETag>"a024268b53f21f3cffe67c84202b6c37"</ETag></Part>
<Part><PartNumber>4</PartNumber><ETag>"04da279d88080c80dcdef0fa6c2cb047"</ETag></Part>
</CompleteMultipartUpload>
Make sure that the PartNumber is correct here. It's an easy mistake to accidentally use the order of upload completion here rather than the number of the upload part. If this is not the case, you will get the error you saw, even if a part with said ETag does exist on S3.