Is the AWS Elastic Beanstalk 502 bad gateway error causing trouble? Talk to our AWS Support services, and say goodbye to this error. 

How to fix 502 Bad Gateway AWS Elastic Beanstalk

If you have been running into HTTP 502 bad gateway errors in the AWS Elastic Beanstalk environment, you have come to the right place.

In most cases, the services resume after a few seconds of the error popping up. Before we dive into how to fix this error, let’s take a look at the root cause behind this issue.

The HTTP 502 error often occurs when the web server, gateway, or proxy server gets an invalid response from a backend server. The error can be thrown by any one of the components of the AWS Elastic Beanstalk.

Our experts suggest checking the backend and ELB response code for the request to find the source of the error. The access log entry will have two fields, namely, elb_status_code and backend_status_code.

These codes help us determine the source of the AWS Elastic Beanstalk 502 bad gateway error.

Alternatively, we can check the load balancer Amazon CloudWatch metrics to find the errors under the HTTPCode_Backend_5XX metric. Usually, we can find 502 errors under the HTTPCode_ELB_5XX metric.

Let’s take a look at how our in-house experts resolve the 502 bad gateway error.

One of our customers contacted us when they received the following 502 error:

In this scenario, the error is being thrown by the Nginx server due to an invalid response from the tomcat server. Hence the Tomcat is the cause behind the error in this case.

In order to resolve the AWS Elastic Beanstalk 502 error, our Engineers ran the open-source yCrash script on the EC2 instance in which the tomcat server was running.

This captures different artifacts from the technology stack. On examining the kernel log file they found the following error message

Out of memory: Kill process 24458 (java) score 874 or sacrifice child

Hence, the Tomcat server terminated the process due to excessive memory consumption. In other words, the kernel terminates the tomcat server each time the app’s memory consumption exceeds the capacity limits.

Furthermore, the EBS service automatically restarts the tomcat server each time it terminates. Our experts resolved the issue by upgrading the EC2 instance RAM capacity.

If you are not able to narrow down the root cause behind your AWS Elastic Beanstalk 502 bad gateway error, contact our experts today.

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

Conclusion

To wrap things up, our skilled Engineers showed us how to find the root cause behind an AWS Elastic Beanstalk 502 bad gateway error. We also got a firsthand look at how to resolve the issue when it originates in the Nginx server.