Firefox 137 hangs and will not resolve most sites now

[BetaOne]

The Firefox 137 update ruined smooth browsing.  Almost all common sites either hang, fail to load  or pop up a DNS failure screen.  This version totally broke something that worked fine.  All my other browsers work fine and all my security programs with internet protection work except with Firefox now.  Firefox 137 is the problem through process of elimination.  All my computers do the same thing.  Banking sites either do not load or display a DNS error.  Amazon will not do anything past the log in screen.  Common sites with ads either run very slow or do not run at all.  Turning off Enhanced Protection does nothing.  This all started with the 137 update.  Whatever is causing this is consistent across all the computers we use.  In fact, it hung sending me the log-in confirmation via email for this forum.  Had to do it twice to get it to send.

[zebedee]

Try going to Help|More Troubleshooting Information|Clear startup cache, then restart Firefox. I had a problem with security certificate failures on multiple sites after upgrading to 137.0, this solved the issue. YMMV, of course.

[BetaOne]

That actually made it worse for some reason.  Most sites will not function as before. Something is amiss in the new security functions.  Most of the usual fixes did not work.  Might be time to delete and install a fresh copy.  If it was related to my antivirus settings or UDM SE settings it would be affecting all my browsers.  Edge and Opera work fine, I do not run Chrome

[zebedee]

Oooops! There is a "Refresh Firefox" button you can try before a full reinstall, but it will uninstall all your extensions.

[Anonymous]

See my question about these same issues, "Firefox 137 updated..." posted and edited several minute before I sent this reply. Any real answers I'd appreciate them, Thanks.

[BetaOne]

Today's update made things worse.  Now the browser hangs and will not load more sites.  Sigh....

[Starefossen]

Exact same issue with 138.0b4 (aarch64) on macOS 15.4 (24E248). Firefox completely gives up resolving DNS names, other apps and system tools (like nslookup) is working just fine.

[foxxxymox]

Me too... strangely in a different user account, Firefox is fine, but on the primary one, which has lots of tabs open, it seems to be spinning out at the DNS resolution stage of a page load, and also hangs when you try to quit.  macOS 15.4.

Actually I see that a bug has been filed:

https://bugzilla.mozilla.org/show_bug.cgi?id=1958140

I have tried refreshing the browser, clearing startup cache, but still having the same problem.  My Firefox build ID is 20250327043313.

[BetaOne]

I have 4 computers with Firefox.  The one I leave offline and decline to update FF136 works fine when I connect to the internet.  All other machines upgraded to 137 are so unstable with sites not loading, DNS failures, Forbidden connects and lock ups, I've had to abate Firefox for my other browsers that have no problem connecting to sites with 2 anti-virus programs onboard.  I've been running two AV programs for about 10 years.  I understand the reason to lock down security but it seems they tightened the screws a bot too tight.  At lease add a fail screen that shows why it failed.  A lot of people are having the same problem so it has to be the update.  Amazon, known for tracking, will not run past the landing screen.  If you click on anything in the task bar it just freezes.  Weather radar on Windy Weather site has not been able to run since the update.  Kind of put me in a bind with very severe weather the other day.  Even National Weather Service radar would not run.  Some sites just lock the browser up.  I've sent broken sight reports for at least 10-15 sites that will not run on FF137.  My one machine at 136 runs fine.

[foxxxymox]

Fortunately the bug i linked to above shows that it has developers' attention.  Though to be honest, this bug is such a show-stopper, I don't know how 137 was released.  I'm curious how prevalent it is.

[BetaOne]

I give up.  The browser simply does not work anymore.  I have done everything to try and fix the issue but the issue just can't be fixed on my end.  Firefox 137 is the issue.  All my other browsers work fine even when using a VPN and other AV settings.  I guess I'll find something else. My issues are not isolated and at this point I do not know what Firefox's future is if they can't fix it.

[BetaOne]

Well, a refresh and even removal/reinstall did nothing to fix the issue.  I wonder how much longer this will continue.  I have been seeing a lot of consistent comments all over the web.  They all basically state the browser will not resolve sites.  The .01 update made the issue worse. The problem is consistent across other operating systems.  I wish they would push a roll-back, fix 137 and try again.

[foxxxymox]

Solution found!

The bug I linked to above suggested it was something with the Mac Keychain, and indeed I'd had a bunch of crap in there that I'd been meaning to clean out.

Long ago I had added keychains from another user account I was trying to recover the passwords from. (a)  There were also keychains in there from a drive I had recovered for a friend, the original files which had been deleted yet I could not delete the references inside keychain. (b)

In the case of (a), I just had to remove the keychain – that fixed Firefox!

In the case of (b), in case anyone else is in this situation, and it may help you too, I decided it was time to figure out how to clean up this crap.  I don't know whether I had to disable System Integrity Protection in order to complete this step, but I had already done so in my troubleshooting, and if you need to, follow the instructions here.  Make sure to turn it back on when you're done!

In terminal, use the following command:

security list-keychains -s /Users/<user_account>/Library/Keychains/login.keychain-db

replacing <user_account> with your own.  Now my keychain is clean and Firefox is resolving DNS properly.