Yesterday, all of a sudden, Firefox 147.0.2 (64-bit) became fucked up under Windows 11. It wouldn’t open certain sites, which Edge would open on the same laptop. The same version of Firefox opened the respective sites just fine under Debian 13.

I struggled with Kimi (K2.5 Thinking) to troubleshoot it.

There was no Advanced button on the error page, because: “The connection to www.acer.com was interrupted while the page was loading.” The error (F12, Network) was NS_ERROR_NET_INTERRUPT.

Setting network.dns.disableIPv6 to TRUE didn’t help.
Setting network.http.http3.enabled to FALSE didn’t help.
Setting security.tls.version.max to 3 didn’t help.
And network.trr.mode was already 0.

But the page did load in a Private Window (Ctrl+Shift+P)!

It wasn’t because of an extension. It was because of corrupt cookies! So many other suggestions by Kimi needed not to be tried.

To avoid “nuking everything,” Kimi’s suggestion was rock-solid: when a page won’t open, click on the lock, then “Clear cookies and site data” for that site only.

Good to know.

Fucking stupid, shitty Firefox.