Error 521 for wordpress based website with Cloudflare version 3.4.1

Hi Team,

I am facing Error 521 for one of my website. I have cloudflare installed in my other webiste applications on Linode server which are working. Cloudflare version is 3.4.1 in all the applications.

Initial fixers I tried are as follows:-

Ensure your origin web server is responsive - Yes it is responsive.
Review origin web server error logs to identify web server application crashes or outages. - It is showing php-fpm segmentation fault. I restarted php-fpm but it didnot fix the issue.
Confirm [Cloudflare IP addresses] are not blocked or rate limited - None of the IPS are blocked.
Whitelist all Cloudflare IP ranges 2 in your origin web server’s firewall or other security software
Also I reviewed the additional steps to rectify this but unfortunately couldn’t get it working.
Can somebody give some insight on how to debug this further or fix it permanently. Also let me know if any configuration issues might cause this problem.

Error SS [ ]


3 Replies

It looks like you've tried the steps that are listed on CloudFlare's site for the 521 error. I do want to link you to a post in their forum which gives some extra tips that you can look into:

Community Tip - Fixing Error 521: Web server is down

I want to address the PHP Segmentation fault error that you're receiving by linking you to one of our other posts here in the Linode Community which addresses this, as that error could be the cause of the issue:

PHP-FPM Segfaults

I already have tried this but it's not working.


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