*Note*: Sending before Privacy, WP Security, and Adoption approvals, due to
short timeline to M149. I do not expect significant feedback from those
channels as this is a small change to an existing API that already has
support from WebKit where relevant (for the Payment Request API part).

*Contact emails*
[email protected], [email protected]

*Explainer*
https://github.com/w3c/payment-request/issues/1040

*Specification*
https://w3c.github.io/payment-request/#payment-handler-indicates-an-internal-error-algorithm

*Summary*
Enables payment handlers that are accessed via the Payment Request API to
return distinct errors for "user cancelled" vs "internal payment app
error". This allows web developers to build better flows for users, e.g. by
retrying or falling back to a different flow when an internal app error
occurs, whilst properly stopping the flow if the user wants to cancel. The
Web-based Payment Handler API can indicate this difference based on what
error they use to reject the promised passed to
PaymentRequestEvent.respondWith. If the promise is rejected with an
OperationError, then "internal app error" (OperationError) is returned to
the merchant via the PaymentRequest.show(), otherwise "user cancel"
(AbortError) is returned. Native app payment handler infrastructure is
similarly updated, but is out of scope for web APIs.

*Blink component*
Blink>Payments
<https://issues.chromium.org/issues?q=customfield1222907:%22Blink%3EPayments%22>

*Web Feature ID*
payment-request <https://webstatus.dev/features/payment-request>

*Motivation*
Currently, when PaymentRequest.show() is rejected due to an error in the
underlying payment handler app, the only possible outcome is AbortError.
This makes it difficult for payment apps using Payment Request to build
good user flows, as it is difficult to differentiate between "call failed
because user cancelled out of the payment app" and "call failed because the
app had an internal error".

*Initial public proposal*
*No information provided*

*TAG review*
N/A - very minor API tweak (was briefly discussed with TAG member at TPAC
2025, who showed no concern)

*TAG review status*
Not applicable

*Goals for experimentation*
None

*Risks*
*Interoperability and Compatibility*
*No information provided*

*Gecko*: N/A Firefox does not ship Payment Request or Payment Handler.

*WebKit*: Positive (https://github.com/w3c/payment-request/pull/1050) Positive
for the Payment Request change, N/A for the Web-based Payment Handler
change as WebKit does not implement any Payment Handler other than Apple
Pay (PR was reviewed by marcos @ webkit, who is doing their implementation)

*Web developers*: Positive Requested by both current + prospective payment
handler adopters

*Other signals*:

*Ergonomics*
No expected ergonomic risks.

*Activation*
No expected activation risks - minor change adding a new error outcome for
PaymentRequest.show()

*Security*
No known security risks.

*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?
This adds a new potential (error) return value for the
PaymentRequest.show() API within WebView. This is considered low risk, both
because a new error type shouldn't be a significant risk but also because
PaymentRequest in webview is **disabled by default** and must be manually
enabled by the webview embedder.


*Debuggability*
Standard devtools debugging; breakpoints + introspection of error types.

*Will this feature be supported on all six Blink platforms (Windows, Mac,
Linux, ChromeOS, Android, and Android WebView)?*
Yes

*Is this feature fully tested by web-platform-tests
<https://chromium.googlesource.com/chromium/src/+/main/docs/testing/web_platform_tests.md>?*
No
Manual WPTs added where possible -
https://github.com/web-platform-tests/wpt/pull/59002, but Payment
Request/Web-based Payment Handler do not have the necessary chromedriver
automation currently to write fully fledged automated tests. Chrome source
automated tests added as well, of course.

*Flag name on about://flags*
*No information provided*

*Finch feature name*
PaymentRequestSupportReportingAppError

*Rollout plan*
Will ship enabled for all users

*Requires code in //chrome?*
Technically, a tiny bit (UX code for web-based payment handlers, some
browsertests are also in //chrome)

*Tracking bug*
https://crbug.com/473478138

*Availability expectation*
Payment Request level changes will be available in both Chromium and
Safari, but Safari only supports Apple Pay as a payment method. Chromium
browsers will also support both the web-based Payment Handler and native
app Payment Handler support for it.

*Estimated milestones*
Shipping on desktop 149
Shipping on Android 149
Shipping on WebView 149
*Anticipated spec changes*

No open issues, although the general question of whether a single new error
type (vs something generic like supporting arbitrary developer errors to be
passed through) was debated between us and Apple. Marcos is following up
with the TAG on the general principle because it's also relevant to the DC
API. This might cause future changes, but they would likely be *mostly*
backward-compatible (since OperationError would remain a valid error type
to throw).

*Link to entry on the Chrome Platform Status*
https://chromestatus.com/feature/5942637229113344?gate=4777865385213952

This intent message was generated by Chrome Platform Status
<https://chromestatus.com/>.

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