Error 521 is the most common error on Cloudflare. In fact, it’s no exaggeration to say that all Cloudflare users will experience this error at least once.
Fortunately, because of its general nature, you can easily deal with this 521 error. But before that, let’s find out what error 521 is and why it can suddenly appear.
What is Error 521 Web Server is Down?
In short, error 521 is a WordPress error that occurs when your WordPress server refuses to connect with Cloudflare. In effect, Cloudflare will display error code 521.
This is because the browser has successfully connected to the Cloudflare server. However, when Cloudflare wants to forward the connection to your website, it gets rejected.
What Causes Error 521?
Usually, the cause of the 521 error is due to two things, namely:
1. Server Down
Error code 521 often appears because your WordPress server is down. So no matter how hard Cloudflare tries to connect, your website will reject it because the server is down.
2. False Detection (False Alarm)
Cloudflare is a Content Delivery Network. It works as a liaison (proxy) between the visitor’s browser and your website. Due to its proxy nature, Cloudflare accesses your WordPress server with the same IP often. In fact, the IP of each visitor should be different.
Well, that’s why your server security system might consider it a hacker attack. This is because the server detects the amount of traffic coming from IPs that are similar to one another. As a result, the server will block the Cloudflare IP and an error code 521 will appear.
How to Overcome Error 521 Web Server is Down
After you are more familiar with the 521 error, here we provide three easy ways to overcome it:
1. Check if the Server is Online
Since the most common cause of 521 is server down, the first step you should take is to check the status of the server. Because, if the server does die, method number two and three won’t work.
So, to check the server status, you need to run the Curl Command. If you use Linux or Mac, you can run it directly through the Terminal.
However, if you are using Windows, you can check it via this site.
https://tools.keycdn.com/curl
All you have to do is enter the IP address of your WordPress server (started with http://) in this box and click Check
2. Give Access to Cloudflare IP
What if the server is online and error 521 still appears? So, that means you have to give access or whitelist all Cloudflare IPs so they aren’t blocked by the server.
You can do this by editing the .htaccess file and making sure that all Cloudflare IPs are unblocked.
Oh yes, if you are confused or hesitant to edit the .htaccess file, just contact the hosting provider directly. You can ask for their help to edit it.
3. Change SSL Settings
If you are a new Cloudflare HTTPS user, your server may not be set up to accept access from Cloudflare’s IP address on port 443. Therefore, you might try using Flexible SSL on Cloudflare instead of Full SSL.
You can change SSL by logging into the Cloudflare dashboard, then the SSL/TLS menu and selecting Flexible.
Fix Your 521 Error Now!
You can see above that the 521 error is closely related to the website server. Where usually you are required to contact the hosting provider. Therefore, it is important for you to choose hosting with customer support that is on standby 24 hours if error 521 suddenly appears.
If you are a webhosting user and are still experiencing error 521, immediately contact your hosting provider’s customer support via the available livechat!
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