Firefox Intermittent 502 Errors


we started getting 502 errors on Firefox only. They are kind of alternating. If I continuously refresh the page, I get one 502 error, one normal page, one 502 error, one normal, …

The site is behind AWS load balancer. The same thing does not happen on Chrome and also if I take Cloudflare proxy out and serve DNS only it works fine on Firefox again.

Does anybody have any ideas?


We are on paid plan. So, that’s not the issue here. Also, I’m not sure the issue I have is the same. I’m getting 502’s not 520’s. And, I am only getting them on Firefox never on Chrome.


May I suggest looking at the below articles:

Have you checked if you block any Cloudflare connections to your origin host / server?
Like if you have some Firewall or?
In this case, kindly follow the instructions from the below article to whitelist and allow Cloudflare to connect to your origin host / server if so:

Cloudflare IP addresses list can be found here:

Where is your AWS lb hosted? I’m also seeing some 502s in Singapore from Linode VM…

still figuring things out

None of this applies. As I said, this error only appears on Firefox and never on Chrome for multiple people who tried. When any of us uses Firefox, we see these 502’s randomly. But, same person same pc with Chrome never sees them.

Our lb is in US Gov East

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