You just introduced a new "HTTPS-Only Mode" -- as of the last version or two, it no longer allows access to an "http://" site. All such sites are blocked only by Firefox. Is there a fix?

Yes, I see it for the non–apex domain: Narrowed nightly regression window from [2026-08-04, 2026-08-06] (2 days) to [2026-08-04, 2026-08-05] (1 days) (~0 steps left)

11:37.95 INFO: Got as far as we can go bisecting nightlies...
11:37.95 INFO: Last good revision: 2cf8eec95457451adbd67d223a7af8ed65461fcd (2026-08-04)
11:37.95 INFO: First bad revision: bb3ac5a217ffe1d7fc66eb86f4af7f6e113d9054 (2026-08-05)
11:37.95 INFO: Pushlog:

https://hg.mozilla.org/mozilla-central/pushloghtml?fromchange=2cf8eec95457451adbd67d223a7af8ed65461fcd&tochange=bb3ac5a217ffe1d7fc66eb86f4af7f6e113d9054

Before trying to bisect to the actual change, I see one potential patch there bugzilla.mozilla.org/2056195 which refers this regression: bugzilla.mozilla.org/2066852 — sounds good to me.

I can confirm the above URL works again in 156.0 Beta 4 so this should be fixed in a release next week. Thanks for the report!

Thanks jbr

I rechecked and see that the http:// dk0wcy de (no www) is working OK now in Firefox 155.0.1 so something has changed somewhere since yesterday. very strange. still redirects to https:// when adding www

Glad to hear that the 156.0 release should fix the issues fully.

Thanks Tony J

The long read is in the standard support timeline bugzilla.mozilla.org/1869075 for the service records in DNS content to speed things up — the potential workaround/preference to skip that spec is mentioned in bugzil.la/2066852#c5 but for anyone willing to download the separate Beta or Nightly firefox.com/channel that'd be the best validation any private or specific hosts work as expected for you.

Hi there,

Could this be a regression in Firefox 155 related to how DNS over HTTPS interacts with HTTP connections?

From the testing shared here, the site works normally when DoH is disabled, but when DoH is enabled Firefox appears to upgrade the HTTP request to HTTPS, even though HTTPS-Only Mode is set to “Don’t enable.” The fact that similar behavior has been reproduced with different DoH providers and on different machines makes this particularly interesting.

Could Firefox 155 have changed something in the way DoH responses are handled when deciding whether an HTTP connection should be upgraded to HTTPS? And if HTTPS-Only Mode is disabled, should DoH have any influence at all on whether Firefox upgrades an HTTP URL?

Has anyone been able to confirm whether this is expected behavior in Firefox 155 or an actual regression that should be reported as a bug?

Hi Danny

Yes, it is a regression in 155.0 and / or 155.0.1 and jbr confirmed that there are two bugs open which should be fixed with the release of 156.0 next week.

Thanks Tony J

The links to the RFC 9460 timeline are in the post right above.

(v156.0 RC1 is already built, if anyone wants to update from the release server ahead of time, if using an unstable channel didn't sound appealing.)