404 - Not Found error on static website

Hey there,
Based on the S3 HTTP response code document in https://docs.aws.amazon.com/AmazonS3/latest/dev/CustomErrorDocSupport.html

• The URL of the website refers to an object that does not exist
• The request is for an index document that does not exist
• A bucket specified in the URL does not exit
• A bucket specified in the URL exists, but isn’t configured as a website

To troubleshoot check if the following factors are met
• Ensure that you have configured and uploaded an index document that exactly matches the index document name that you enter in the static web hosting dialog box.
• Also ensure that the error document name exactly matches the file name of the html error document that uploaded to your s3 bucket

For reference on configuring index document, check this link
https://docs.aws.amazon.com/AmazonS3/latest/dev/IndexDocumentSupport.html

I hope the provided information helps
Have a great day