Page could not be loaded

[JoyFreak]

I have been experiencing random page not loads with Safari on iOS but, a different/related issue when I tried other borrowers (Chrone and Chrome based Ecosia) . But in that case it was not page not load but loading without any CSS/LESS formatting and js not running. I few days ago I did disable HTTP/3 as @MattW suggested I try in relation to another Mir reproducible CF issue I was having, ie PayPal IPNs failing. I’m still getting those but not had any of the random oage not loading issues.

NB: what I found with the iOS Chrome issue was that it only happened on a page refresh via the browser, not via e.g. going to another or same page via the xenforo navigation. So I could happily tap on New posts repeadly but then a browser refresh would cause/manifest the issue.

Maybe it’s related to the theme or conflicting add-on?

 

[Mr Lucky]

Maybe it’s related to the theme or conflicting add-on?

Not theme because switching to default doesn’t change anything. Addon is hard to tell. I just thought it seemed associated with what people are saying in this thread.

 

[arn]

Do you have rocket loader or auto minify on Cloudflare?

 

[Mr Lucky]

Do you have rocket loader

No

or auto minify on Cloudflare?

Unlikely because I don’t even know where it is. I’ve changed very little from default.

 

[Mr Lucky]

Do you have rocket loader

No

or auto minify on Cloudflare?

Unlikely because I don’t even know where it is. I’ve changed very little from default.

 

[Xon]

This is effecting one of my clients, and disabling "HTTP/3 (with QUIC)" hasn't helped

I'll try disabling "0-RTT Connection Resumption" and see if that helps

 

[woody]

I have a report with a member browsing with Firefox, awaiting to see of the http3 switch solve his issue.

"Be careful. Something doesn’t look right. Firefox spotted a potentially serious security issue with www.domainname.com. Someone pretending to be the site could try to steal things like credit card info, passwords, or emails"

 

[Filetrip]

I logged in to state that this has been happening to our site gbatemp.net too
I will try turning off the HTTP3 option in Cloudflare, hopefully this will help

For anyone looking for the setting, it's in "Speed -> Settings -> Protocol Optimization"
View attachment 337053

This seems to have worked - it's been good for several days now.

Initially I thought it didn't, because I had the error one more time even after changing the setting. But then it stopped happening.

It's possible that the browser had "cached" the fact that it was expecting HTTP3, and it didnt work one single time, then, upon clicking "Reload page" it "downgraded" its expectations to HTTP2, and subsequently, I can confirm that the site has been working/loading properly and I didn't get the error page anymore.

I don't really know what I'm talking about so this could be BS, but this is just what I've observed.

 

[arn]

This is effecting one of my clients, and disabling "HTTP/3 (with QUIC)" hasn't helped

I'll try disabling "0-RTT Connection Resumption" and see if that helps

The http/3 thing seemed specific to Safari issues. And supposedly Safari hangs on to that for 24 hrs or so.

This seems to have worked - it's been good for several days now.

Initially I thought it didn't, because I had the error one more time even after changing the setting. But then it stopped happening.

It's possible that the browser had "cached" the fact that it was expecting HTTP3, and it didnt work one single time, then, upon clicking "Reload page" it "downgraded" its expectations to HTTP2, and subsequently, I can confirm that the site has been working/loading properly and I didn't get the error page anymore.

I don't really know what I'm talking about so this could be BS, but this is just what I've observed.

safari caches that setting for up to a day apparently

 

[arn]

I have a report with a member browsing with Firefox, awaiting to see of the http3 switch solve his issue.

"Be careful. Something doesn’t look right. Firefox spotted a potentially serious security issue with www.domainname.com. Someone pretending to be the site could try to steal things like credit card info, passwords, or emails"

This just sounds like a ssl certificate issue

 

[VBX Co]

Thanks. Visitors have reported similar behaviour so have also disabled HTTP/3 (with QUIC).

 

[xanacle]

I have this issue right now and it hasnt been turned off for the past 12 hours and nobody responds to my ticket, and my members are upset.

 

[Kirby]

We also got complaints about connection errors from a bunch of users since about 2026/05/01 and I got one myself yesterday evening (on Android with Chrome).

I've disabled HTTP/3 now, let's see if that helps.

 

[Xon]

After switching from the Let's Encrypt SSL cert to Google Trust Services for the SSL cert (as modern let's encrypt can have a compatibility issue with iOS 13 or older), and disabling HTTP/3 (QUIC) the issues appear to be resolved for my client.

The ticket from Cloudflare had this as the "explainer" for the http/3 (quic) issue, but only once I mentioned that I disabled this option.

You have identified the root cause correctly. Disabling HTTP/3 (QUIC) resolved the connection failures because there are known compatibility issues between Safari on iOS and the QUIC protocol, particularly in certain network conditions. When a QUIC connection attempt fails, some Safari versions do not fall back to TCP/HTTP2 reliably, which results in the connection being dropped entirely rather than retried over a more compatible protocol. From Cloudflare's side, this surfaces as 499 errors, as the client closes the connection before it completes.

This is a browser-side limitation rather than a configuration problem on your zone. Keeping HTTP/3 disabled is a perfectly valid long-term choice if your user base is predominantly iOS/Safari users and connection reliability is a priority.

It took an annoyingly long time to get to that point, and they didn't suggest the http/3 (quic) option may be the cause.