You must use a "content type" of "application/json" when you upload to an S3 bucket. You can specify that as party of the upload process. If you don't, S3 may store your file with a BOM marker. That may cause the error you see from Roku.
Ive been experimenting all morning .... when uploading my feed file to the s3 bucket should I upload my saved roku JSON feed manager file with the .json extension or should I copy and paste the text in the buckets cors configuration tab I’m still getting the same error when I put the bucket url into the roku dp
Regardless of what service you use, you need to upload the actual feed file (.json). It's the URL of that file that Roku is looking for in the developer portal.
Ok I’ve created the bucked I’ve turn off the privacy settings and made the bucket accessible to the public I’ve then uploaded the .json file to the bucket ... do I need to do anything with core settings or change any of the object permissions or change default set properties before I finalize the upload
As long as the bucket is public, no other settings are required.