Firefox Release Notes "Developer Information" Link is Broken

Hi

Thank you for letting us know, but that now appears to be fixed.

Thanks for the response. Sorry for clicking "solved" too soon.

I still see the issue. Exact steps to reproduce:

1. Navigate to https://www.firefox.com/en-US/firefox/153.0/releasenotes/
2. Scroll to the "Developer" section
3. Click the Developer Information link (https://developer.mozilla.org/docs/Mozilla/Firefox/Releases/153 )
4. MDN displays a "Page not found" message with a list of search links to try, the first displayed being "153"
5. Click the "153" link (https://developer.mozilla.org/en-US/search?q=153 )
6. Click the link for "Firefox 153 release notes for developers (Stable)" in the list of results and the developer release notes are displayed

Notice the difference between the URL for the link in the Firefox release notes page and what works in MDN - the former's URL is missing the "en-US" which seems to be required for it to open in MDN and is not automatically added by the server.

Screenshot of message MDN displays when attempting to use the link in the standard Firefox release notes page is attached.

Let me know if I can provide any additional information.

No worries, that bit was not overlooked — it's deliberately published without hard–coded locale to let MDN serve you your accept–language preference. It seems working as expected for everyone; I intentionally run browsers with empty or malformed accept–language headers and still get this locale fixup to default en–US as expected there.

Do you only see this for v153 release notes or any of the previous versions exhibit the same?

I checked from a couple of CLI/headless locations and it all seems to work as expected so this would be interesting to understand what's different on your end:

--- ignore - updating this resulted in the new answer added below (?) ---

Sorry for the delayed response.

I checked the release notes pages for various versions and their one-offs going back to 148.0 before concluding that the issue is not limited to just the release notes page for 153.0 (at least for decently recent releases).

It is caused by the "/en-US/" not being included in the pathname for the link's URL, so I think that needs to be addressed in one way or another. MDN just does not handle the URL set in the release notes page and will complain and suggest as I described earlier on.

Manually adding "/en-US/" to the URL set for the clicked link in the address bar while the MDN 404 page is visible does result in the developer notes opening. This simple test goes with what I described regarding the use of the suggested search links MDN presents.

All normal steps such as clearing cache, cookies, etc. have been completed multiple times (manually and via the option to do so when quitting Firefox which I have had set for a while). I do not think I would be working with stale data.

I hope this helps.

As mentioned above, the links are deliberate, and are expected to negotiate the language with the browser. And if they fail, they default to /en-US/ … why a) your connection doesn't is a mystery, b) how you'd even be able to get anything served from the MDN hosts on this path is another mystery.

I suggest you file that somewhere more actionable as github.com/mdn/mdn-community — and record a HAR (network capture) showing what gets sent and what is received, to help inform the status codes exchange for the maintainers to look into.