I am using Firefox latest version to test my website running mp3 files fetched via proxy We are using cookie authentication to validate user and play audio file Here is our current implementation We send a request to our media proxy with a user token and it validates and set a cookie in response with a mp3 URL We set this mp3 URL in audio src and cookie is saved in browser The problem is that <audio> player fetch media from src but it does not send the cookie we saved for that media proxy instead it does not send a single request cookie although in our XHR call we were sending many cookies When no cookie is sent to our media proxy a 401 response is sent and audio player stops Here are some requests from workflow XHR Response ----------------------- HTTP/2.0 200 OK date: Mon, 03 Jun 2019 07:21:45 GMT content-type: text/plain;charset=UTF-8 content-length: 10 access-control-allow-credentials: true access-control-allow-origin: https://consumer.example.com set-cookie: x-id-token=********** expect-ct: max-age=604800, report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct" vary: Accept-Encoding server: cloudflare cf-ray: 4e0fe97e6ccfd791-MRS X-Firefox-Spdy: h2 XHR Request ---------------------------- Host: media.example.com User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:67.0) Gecko/20100101 Firefox/67.0 Accept: application/json, text/plain, */* Accept-Language: en-US,en;q=0.5 Accept-Encoding: gzip, deflate, br Referer: https://consumer.example.com/listen/uuid Origin: https://consumer.example.com Connection: keep-alive Cookie: ajs_anonymous_id=%22f6ae4eca-8ea9-4560-86e3-627457ef4a81%22; _gat=1; __cfduid=d695230e812d89679db4755d7f0b1cc311559546465; optimizelyEndUserId=oeu1559546469968r0.12488801925201709; tracking-preferences={%22version%22:1%2C%22destinations%22:{%22Amazon%20Kinesis%22:true%2C%22Branch%20Metrics%22:true%2C%22Google%20Analytics%22:true%2C%22MailChimp%22:true%2C%22Optimizely%22:true}%2C%22custom%22:{%22marketingAndAnalytics%22:true%2C%22advertising%22:true%2C%22functional%22:true}}; ajs_user_id=%221bd49c39-b295-4e31-87af-1ac3745190fb%22; ajs_group_id=null; _ga=GA1.2.1103036539.1559546471; _gid=GA1.2.2051257759.1559546471; fbsstage=***** After this request i see that X-Id-Token cookie set in browser but in a subsequent call to same URL not even a single cookie is sent although in above request 4-5 cookies were sent Subsequent Request --------------------------------- Host: media.example.com User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:67.0) Gecko/20100101 Firefox/67.0 Accept: audio/webm,audio/ogg,audio/wav,audio/*;q=0.9,application/ogg;q=0.7,video/*;q=0.6,*/*;q=0.5 Accept-Language: en-US,en;q=0.5 Referer: https://consumer.example.com/listen/uuid Range: bytes=0- Origin: https://consumer.example.com Connection: keep-alive TE: Trailers expect-ct: max-age=604800, report-uri="https://report-uri.cloudflare.com/cdn-cgi/beacon/expect-ct" server: cloudflare cf-ray: 4e0fe9823aecd791-MRS X-Firefox-Spdy: h2 This works fine in chrome as the cookie is sent in all requests but not in firefox. There is no CORS issue in browser console. I see only these errors from audio player AbortError: The fetching process for the media resource was aborted by the user agent at the user's request. AbortError: The operation was aborted. AbortError: The operation was aborted. This happened because the media fetch call returned 401 because cookie was not present Can anyone tell me whats wrong here?