1677379 - "Learn more" link for specific CORS error is a 404 (CORSMissingAllowHeaderFromPreflight)

Status: RESOLVED FIXED

(DevTools :: Console, defect, P3)

Description

[Miriam Vellacott [:miriam]]

User Agent: Mozilla/5.0 (X11; Ubuntu; Linux x86_64; rv:81.0) Gecko/20100101 Firefox/81.0

Steps to reproduce:

Send a POST request to a server at a different domain that doesn't set the "Access-Control-Allow-Headers" header and specify a header.

Actual results:

The correct error:

Cross-Origin Request Blocked: The Same Origin Policy disallows reading the remote resource at https://chess-api.polytopia.win/accounts/login. (Reason: header ‘content-type’ is not allowed according to header ‘Access-Control-Allow-Headers’ from CORS preflight response).
With a [Learn More] link pointing to the following URL:
https://developer.mozilla.org/docs/Web/HTTP/CORS/Errors/CORSMissingAllowHeaderFromPreflight2
Which 404s.

Expected results:

Learn more link should not 404. Perhaps it was meant to be

https://developer.mozilla.org/docs/Web/HTTP/CORS/Errors/CORSMissingAllowHeaderFromPreflight

Comment 1

[Miriam Vellacott [:miriam]]

Sorry for the bad markup I'm new to this forum.

Comment 2

[Nicolas Chevobbe [:nchevobbe]]

Thanks for the report! I was able to reproduce and I have a fix for this.

Comment 3

[Nicolas Chevobbe [:nchevobbe]]

I think this came with Bug 1575068

Comment 4

[Nicolas Chevobbe [:nchevobbe]]

Attachment: Bug 1677379 - [devtools] Fix Learn more link on CORS warning message. r=ckerschb.

In Bug 1575068, the message of CORSMissingAllowHeaderFromPreflight and CORSPreflightDidNotSucceed
changed, and the category field was updated in the nsIErrorMessage. As a result, the keys in
errordocs.js needed to be changed, which was rightfully done, but the value was changed as well,
which means the resulting url of the Learn more links were modified as well. I'm not sure if
something changed since then, but those 2 urls now lead to 404 pages on MDN.
This patch fixes those URLs to ensure we do link to the right MDN pages.

Comment 5

[Pulsebot]

Pushed by [e-mail]:
https://hg.mozilla.org/integration/autoland/rev/3c200b6e7fee
[devtools] Fix Learn more link on CORS warning message. r=ckerschb.

Comment 6

[Sebastian Hengst [:aryx] (needinfo me if it's about an intermittent or backout)]

https://hg.mozilla.org/mozilla-central/rev/3c200b6e7fee