I am using Uppy to upload to S3 with signed URLs using @uppy/aws-s3. I already have a server, so I am not using Transloadit. Sorry.
Single uploads work well, which suggest signing and CORS are OK. But when I try multipart uploads, all the preflight OPTIONS calls work, but the uploads themselves fail because they get canceled (not by me).
An example URL that gets canceled:
You can see the partNumber and uploadId at the end.
Any ideas what is causing the cancelation?
Thanks.