Stuck with an AWS ELB Nginx 499 error code? Our AWS Support team is here to lend a hand with your queries and issues.

AWS ELB Nginx 499 error: Causes & Fixes

If you have come across the following entry in the Nginx log with HTTP Status code 499, you are in the right place.

Client Closed Request

One of our customers recently came across this issue when they tried to load a long-running script. The error continued appearing even though the Nginx timeout values were set to 6000 seconds.

According to our experts, the error occurs due to the default value of the Load Balancer’s Idle Timeout parameter. By default, it is set to 60 seconds.

The Load Balancer serves as the middle person between the Client and the Server. Each time the Client makes a request to the Server, the Load Balancer opens a connection and acts as the messenger. In case the Server is unable to respond to the request within the Idle Timeout set by the Load Balancer, the connections are closed automatically.

Although the Load Balancer is responsible for closing the connection, the Nginx assumes it was done by the Client. This results in the AWS ELB Nginx 499 response.

Fortunately, our experts have an easy fix for this issue:

1. First, head to the AWS Dashboard.
2. Then navigate to Load Balancer under EC2.
3. After that, go to Attributes and then edit the Idle Timeout value.

Alternatively, we can fix the issue by forcing Nginx to dynamically look up DNS entries for the ELBs during runtime.

In order to accomplish this, we have to use a resolver in the Nginx configuration with a parameter within the proxy_pass declaration.

For instance, if we are using the Google DNS Name server IP to resolve the public DNS every 30 seconds :


location = /proxy/ {
set $endpoint ;
resolver 8.8.8.8 valid=30s;
proxy_pass https://$endpoint/;
}


Let us know in the comments which one of our solutions helped you resolve the AWS ELB & Nginx 499 error.

[Need assistance with a different issue? Our team is at your service 24/7.]

Conclusion

To sum up, our Support Engineers explained the reason behind the AWS ELB & Nginx 499 error and how to resolve it easily.