Why is Safari not opening websites on macOS Sequoia?

MacOS 15.1

My work around was to use the Safari Technology Preview, but then I updated this last week and the 400 Bad request now happens on that one too. It's a disaster. I am forced to use Chrome on the Gitlab logged in tools, and this issue is to do with some authentication headers - idk.

Works fine on all browsers on multiple OS computers, only Safari has this problem.

See console:

I, too, have been having this issue since

the the first of January

I stop using Safari and switched to Firefox and not issues…

contacted Apple support and they can’t figured out.

For what it's worth, after the Sequoia update, Safari failed to load web sites for me. I tried the obvious without success (reboots, clear cache, etc.). Brave and Chrome had no problems with the same sites. What solved it for me was turning my Wireguard VPN client on and then off (it was off prior to the upgrade). For some reason, that toggle cleared the issue and Safari loads correctly.

Same problem here. Mac mini 2018 (Intel i7, 64GB RAM, 2TB SSD) went from most recent Sonoma to most recent Sequoia. No problems with Sonoma; problems started immediately on using Safari with Sequoia..

Saw some posts/recommendations.

REC#1. Turn off MacOS's built-in optional firewall in the Settings menu. Did that and it worked immediately but after a shut-down and re-start, the problem reappeared with Safari (even with the Firewall off).

REC#2. Remove 3rd-party software/extension from Safari. Did that (had Adguard for Safari installed) and the problem disappeared. Will continue to run with no firewall and no 3P extensions for a short bit to see if problem reappears.

Do you have any VPN or firewall apps installed prior to upgrading? It might be causing the problem. This was true for me and I had to uninstall NordVPN and Lulu firewall, and then reinstall them. Safari now works as expected. Here’s the details of the fix.

Logging into a gitlab instance, the console shows '400 Bad Request' on many of the JavaScript files. Seems to be as other have described an issue with Authorization.

The Safari Technology Preview does not reproduce these issues.

Same thing here. Apple support keeps passing me off to other people and everyone acts like this is a big surprise and I'm the only one...total nonsense. Hours have been wasted on this issue. They need to fix Sequoia 15.

For me, it mostly works, but when accessing web site with Digest authentication, it results in "400 Bad Request". It appears that Authorization header of such requests has a list of fields repeated multiple times, which is clearly a bug. Sometimes it creates a long line with fields repeated over and over. Some web-servers are not happy with that (nginx, for example). Before Sequoia upgrade, everything worked fine.

Ever since upgrading to macOS Sequoia I'm having this problem too on my macBook Air M1, even on macOS 15.1. After some amount of time Safari stops functioning. Pages keep failing to load and the error message "This page was reloaded because a problem occurred" appears. It also sometimes causes the Finder to become sluggish/unresponsive. I already disabled all Safari extensions, but that didn't help. Activity Monitor doesn't show a huge increase in CPU or memory for Safari or any other process. I did once notice that both Rogue Amoeba SoundSource 5 and a Facetime process were red/not responding. Killing those didn't solve the Safari problem. Might be unrelated.

A macOS restart fixes the issue. Until it happens again after a while.

Here's a video showing the problem:

https://www.youtube.com/watch?v=HO1KJVyBSEk

Same here! It's March 29, 2025 and I WAITED to update to Sequoia and on "main" M1 MacBook Air because of the issues my M1 & M2 MacMinis (MacCMini <<<< NO! I'm sticking with MacMins <<<< :-) as I use my MM's to "test" no OS's. Sequoia seemed to improve with the updates since its release last year (no 6 months ago?), but NEW issues are arising which is making it unusable.

FIX PLEASE!!!!🙏🏽 <<< OBTW ... My RECENT Emojis are NOT showing up! WTH?!?!? I mean, its a SMALL issue, but very annoying!

I have the same problem. I finally just made Chrome my default until Apple can fix the problem. Apple you should be shame. Fix the issue.

Yes. Hush plugin was problematic and uninstalling it helped a bit. But on my end, I ultimately have to re-install NordVPN and Lulu app as well to completely fix the problem.

I just installed the Sequoia 15.1 update and the “400 Bad Request” problem persists. Apple seems to have no interest in fixing it.