There is an active effort called that patches the old code to work with new S3 storage backends. If you are a developer, you can self-host the uploader widget on your local machine and point it to the Archive's S3-compatible endpoint.
If you see errors like:
The phrase "Internet Archive HTML5 Uploader 1.6.4" is a technical tag often found in the metadata of items uploaded to Archive.org internet archive html5 uploader 164 best
Below is a detailed breakdown of what this means, why it matters, and how to optimize your use of that uploader version. There is an active effort called that patches
If you are a developer, inject the following into your browser console (F12) before starting the upload: why it matters
Select the option to upload files via the browser (the HTML5 Uploader).