LGTM2
/Daniel
On 2026-07-08 14:15, Yoav Weiss (@Shopify) wrote:
Also, please request review (or n/a) from the adoption checkbox.
On Wednesday, July 8, 2026 at 2:14:50 PM UTC+2 Yoav Weiss wrote:
LGTM1
On Wednesday, July 1, 2026 at 6:24:53 PM UTC+2
[email protected] wrote:
*Contact emails*
[email protected]_ <mailto:[email protected]>
*Specification*
_Fetch Standard: blob URL fetch algorithm_
<https://fetch.spec.whatwg.org/#scheme-fetch:~:text=If%20rangeValue%20is%20failure%2C%20then%20return%20a%20network%20error.>
*Summary*
Blob URL requests made with Fetch or XMLHttpRequest now follow
the Fetch Standard when parsing Range headers. Invalid or
unsupported Range headers fail with a network error instead of
returning the full blob response. This improves
interoperability with other browsers and makes Chromium pass
the corresponding Web Platform Tests.
*Blink component*
_Blink>Network>FetchAPI_
<https://issues.chromium.org/issues?q=customfield1222907:%22Blink%3ENetwork%3EFetchAPI%22>
*Web Feature ID*
_fetch_ <https://webstatus.dev/features/fetch>
*Motivation*
Chromium currently does not fully follow the Fetch Standard
for blob URL requests with invalid `Range` headers. When range
parsing fails, Chromium falls back to serving the full blob
with `200 OK`, whereas the Fetch Standard requires the request
to fail with a network error.
This change aligns Chromium with the Fetch Standard and
improves interoperability for Fetch and XMLHttpRequest range
handling.
It resolves 52 failing Web Platform Tests in total, including
26 failing `fetch/range/` subtests [1] that are part of the
Interop 2026 "Fetch, Uploads and Ranges" focus area [2], along
with 26 corresponding XMLHttpRequest tests [3].
[1] _web-platform-tests dashboard : fetch Blob_
<https://wpt.fyi/results/fetch/range?label=master&label=experimental&aligned&view=subtest&q=label%3Ainterop-2026-fetch%20blob.any>
[2]_web-platform-tests dashboard : Fetch upload and ranges
Interop 2026_
<https://wpt.fyi/results/fetch?label=master&label=experimental&aligned&view=interop&q=label%3Ainterop-2026-fetch>
[3] _web-platform-tests dashboard : xhr blob_
<https://wpt.fyi/results/xhr?label=master&label=experimental&aligned&q=%20blob-range.any>
*Initial public proposal*
/No information provided/
*TAG review*
N/A - no new API or platform design; this is a narrow
conformance fix to existing Fetch Standard behavior.
*TAG review status*
Not applicable
*Goals for experimentation*
None
*Risks*
*Interoperability and Compatibility*
Compatibility risk is expected to be low. This assessment is
qualitative rather than based on dedicated telemetry for the
exact affected scenario.
The change affects only Fetch and XMLHttpRequest requests to
blob: URLs that include an invalid, malformed, or unsupported
Range header. Requests without a Range header are unchanged,
valid single-range requests continue to behave as before, and
non-blob: URL requests are unaffected.
The previous Chromium behavior returned the full blob when
Range parsing failed. This change instead follows the Fetch
Standard by treating such requests as network errors. Firefox
and Safari already implement this behavior, so the change
improves interoperability and aligns Chromium with the web
platform.
The primary compatibility risk is sites relying on Chromium's
previous fallback behavior for invalid Range headers on
blob: URLs. We expect this to be uncommon because it requires
both issuing Range requests against blob: URLs and using
invalid or unsupported Range syntax.
/Gecko: Shipped/Shipping, Firefox already implements this
behavior and passes the corresponding Web Platform Tests
WebKit: Shipped/Shipping, Safari already implements this
behavior and passes the corresponding Web Platform Tests./
/Web developers/: No signals
/Other signals/:
*Ergonomics*
No new API ergonomics risk. Existing Fetch/XHR usage is
unchanged for valid single Range headers; invalid values now
fail as specified.
*Activation*
No developer activation is required. The corrected behavior
applies automatically to blob URL requests with Range headers.
*Security*
No new security risk. The change makes invalid blob URL Range
headers fail instead of serving a full blob response, which is
stricter than current behavior.
*WebView application risks*
/Does this intent deprecate or change behavior of existing
APIs, such that it has potentially high risk for Android
WebView-based applications?/
Low. The risk is no higher for Android WebView applications
than for websites. Only blob: URL requests with invalid,
malformed, or unsupported Range headers are affected; all
other requests are unchanged.
*Debuggability*
Existing Fetch/XHR error handling applies. Invalid blob URL
Range requests surface as a network error / Fetch TypeError,
and valid ranges continue to produce 206 Partial Content.
*Will this feature be supported on all six Blink platforms
(Windows, Mac, Linux, ChromeOS, Android, and Android WebView)?*
Yes
Applies to Chromium platforms that use the common blob URL
loader for Fetch/XHR, including desktop, Android, and Android
WebView.
*Is this feature fully tested by **_web-platform-tests_*
<https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md>*?*
Yes
Covered by Web Platform Tests under fetch/range/, including
blob.any.html and blob.any.worker.html cases for invalid blob
URL Range headers. The CL also updates expectations for the
corresponding XHR blob range tests and adds Chromium unit
coverage for Fetch-compatible single Range parsing and
BlobURLLoader invalid range handling. Relevant CL:
_https://chromium-review.googlesource.com/c/chromium/src/+/7902659_
<https://chromium-review.googlesource.com/c/chromium/src/+/7902659>
*Flag name on about://flags*
/No information provided/
*Finch feature name*
BlobURLFetchRangeHeaderValidation
*Rollout plan*
Will ship enabled for all users
*Requires code in //chrome?*
False
*Tracking bug*
_https://issues.chromium.org/issues/510995915_
<https://issues.chromium.org/issues/510995915>
*Measurement*
No dedicated UseCounter is planned. This is a narrow standards
conformance fix covered by WPT and Chromium unit tests;
invalid blob URL Range header usage is expected to be rare.
*Availability expectation*
Available in Chromium-based browsers once the shipping
milestone reaches stable.
*Adoption expectation*
No active developer adoption is expected because this is a
standards conformance fix to existing Fetch/XHR behavior, not
a new API. Sites using valid single Range headers continue to
work. Sites using invalid blob URL Range syntax may need to
fix that syntax if they currently rely on Chromium returning
the full blob response.
*Adoption plan*
No developer adoption plan is needed. The change ships as a
browser behavior fix and is validated by Web Platform Tests.
Any affected sites should update invalid blob URL Range header
usage to use valid single Range syntax.
*Non-OSS dependencies*
No
*Estimated milestones*
Shipping on desktop
152
Shipping on Android
152
Shipping on WebView
152
*Anticipated spec changes*
None. This implements the current Fetch Standard behavior.
*Link to entry on the Chrome Platform Status*
_https://chromestatus.com/feature/6237991531053056?gate=5496962989293568_
<https://chromestatus.com/feature/6237991531053056?gate=5496962989293568>
This intent message was generated by _Chrome Platform Status_
<https://chromestatus.com/>.
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