HTTP/3 (QUIC) in Beta Chrome availble!

Hi all.

I just tested my Cloudflare Hosted Website using the Beta Version of Chrome
and just saw that my Website Content is served by Cloudflare over HTTP/3 !

Nice see such new Feautures !

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HTTP/3 has been here on and off (mostly off) for a while, but it’s nice that it’s finally in more widespread availability. Now to watch those Analytics for HTTP/3 connections grow from more than an imperceptible sliver.


Yep, Firefox and Chrome have supported HTTP 3 for about a year already.


I rember it was turned On but then turned Off for speed Optimzation at the Data Centers.

Just Tested my Website again and saw a new Record in Loading my Website !

Its really Pitty that there is not yet a InMemory Possibility to store 128 KB of Dynamic Data to be used from inside the Worker as the KV Database sync is 30 Seconds instead the 1 Second needed to avoid and stop Requests to the Origin Server for Dynamic Data.

Without this Request to my Origin Server for Dynamic Data the Website would be Loaded and Rendered in less than < 100 ms Worldwide :-))

Thanks a lot for the Great Work and Support.

Have all a great Time !

It’s Party Time :slight_smile:
Imagination - So Good, So Right (Dim Zach edit)

Hi All.

I was able to test more my Website how it Works with the HTTP/3 QUIC Protocol
and was able to reproduce several times a huge Error when trying to access a Cloudflare Worker Webpage.

The Chrome Webbrowser would just freeze the loading of the Page and after a while switch over to HTTP/2 Protocol.

I can reproduce this Freezing and Blocking over HTTP/3 always when one time the Page is fully loaded over HTTP/3 and then just wait several Minutes wihtout doing anything and then click on the Home Page Link.

It looks like the Cloudflare Implementation of HTTP/3 has a problem when somebody does not refresh a Page after a few Minutes and then try to reload it over HTTP/3

Here two Screenshots of a HTTP/3 Failover when trying to load my Worker HomePage
It takes more than 6 Seconds before it switch over to HTTP/2 and finally load the Website.

I have Enabled also the Chrome NetLog Functionality to Log the Problem and this is what it say.
Hope it is helpfull to Debug the Problem on the Cloudflare side.

As you can see it say 100% Failure.

If needed i can Upload or send the NetLog File of the Logged Session !

I’m not sure about the error, but wanted to add they have a nifty graph so you can see how many of your real users are on HTTP/3.

It’s under Analytics > Performance > Overview

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I also noticed the same problem. Disabling HTTP3 seems to fix the issue. I think it might be affecting Webview as well, like the Facebook In-App Browser. I wonder what’s causing this?

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Few of my job colleagues use Opera and Chrome.

I remember a back in a while, once I switched few Websites to Cloudflare and enabled HTTP/2, they had some strange error due to their Web browsers for HTTP/2, while I did not had them using FireFox.

  • either this topic is for HTTP/3 …

Moreover, I believe support of HTTP/3 is still experimental and not for “consumer” user, and as far as I have tested, I have had issues like loading Revive AdServer (ex OpenX) ads on some Websites, both on FireFox and Chrome when I enable it via about:config / chrome://flags, they would just simply not load or the whole Website loading experience was kind of “long” or freezed because of it.


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