User Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10_15_7) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/94.0.4606.61 Safari/537.36

Expected results:

Spec discussion: https://github.com/whatwg/fetch/issues/1310
Spec PR: https://github.com/whatwg/fetch/pull/1312
Tests PR: https://github.com/web-platform-tests/wpt/pull/31058

Range was added as a safe-listed header as long as the value is in a particular format, which aligns with formats the browser uses when requesting media and resuming downloads.

The following information seems to have sped the development of a webkit patch along, so I will re-post it here:

CORS-safelisted request-header:
https://fetch.spec.whatwg.org/#cors-safelisted-request-header

Allowed particular Range header values (simple range header value):
https://fetch.spec.whatwg.org/#simple-range-header-value

Examples:

Range: bytes=0-255

Range: bytes=255-

Hopefully it will make a patch for Gecko more likely.

Dev docs PR https://github.com/mdn/content/pull/14657

Dev docs published: https://developer.mozilla.org/en-US/docs/Web/HTTP/CORS#simple_requests

Range (only with a simple range header value; e.g., bytes=256- or bytes=127-255)
Note: Firefox has not implemented Range as a safelisted request-header yet. See bug 1733981.

Shipped in Chromium: https://chromestatus.com/feature/5652396366626816
In trunk for WebKit: https://git.webkit.org/?p=WebKit.git;a=commit;h=2b039d303782f915fd730720f281f081aab45549

Edit: Correct link to WebKit: https://trac.webkit.org/changeset/292293/webkit

The Range header was added as a safe-listed header as long as the value
is in a particular format. Update IsCORSSafelistedRequestHeader
implementations to account for this.

Backed out for causing range related wpt unexpected passes.

Push with failures: https://treeherder.mozilla.org/jobs?repo=autoland&resultStatus=testfailed%2Cbusted%2Cexception%2Cretry%2Cusercancel&revision=ee68eebc7bfd59157569f7de331974b06e765482&searchStr=wpt&test_paths=%2Ffetch%2Frange&selectedTaskRun=Y-kmF8pRRZ2joGcNOFesiA.0

Failure logs:

• https://treeherder.mozilla.org/logviewer?job_id=421986327&repo=autoland
• https://treeherder.mozilla.org/logviewer?job_id=421987579&repo=autoland
• https://treeherder.mozilla.org/logviewer?job_id=421986408&repo=autoland

Backout link: https://hg.mozilla.org/integration/autoland/rev/2f3294fbb670

Ah, missed a test that should be passing now.

Backed out for causing failures on general.any.serviceworker.html

Backout link

Push with failures

Failure log

Looks like I was too aggressive in my wpt metadata pruning... The test is failing due to bug 1465074. I'll look to see how easy it would be to solve that bug as well... Otherwise I'll just reduce the wpt test metadata pruning

https://hg.mozilla.org/mozilla-central/rev/cd0d5fa97119

Other MDN docs changes can be tracked in the following GitHub issue: https://github.com/mdn/content/issues/28281