Fix AWS Error Code 500 Internal Server Error (2025)

Updated: 11/29/2025

You open your production site, hit refresh, and instead of your homepage you are greeted with a plain, unfriendly page that simply says 500 Internal Server Error. Your heart drops because this code does not tell users anything useful, it just means the server crashed while trying to process the request. On AWS this can be caused by misconfigured load balancers, failing application code, or overloaded instances, but the good news is that with a bit of structured troubleshooting you can usually track it down and fix it quickly.

Table of Contents

Method 1: Check AWS CloudWatch Logs For the Real Error

The browser only shows a generic 500 status, but CloudWatch usually contains the real stack trace and error message from your application or Lambda function. Before changing anything in production, you want to locate the exact failing component and the time window where the 500s started.

Step 1: Open CloudWatch Logs

Sign in to the AWS Management Console, open the CloudWatch service, and click on Logs. Look for the log group that corresponds to your application, for example your ECS task, EC2 instance agent, or Lambda function that is behind the load balancer or API Gateway.

Step 2: Filter by HTTP 500 Events

Select the most recent log stream and use the Filter events box to search for 500 or for an exception keyword such as ERROR, Exception, or Traceback. Compare the timestamps to the moment when you saw the 500 error in the browser so you can match a user request to a specific log entry and error message.

Step 3: Identify the Failing Component

Once you locate the error log, check whether it points to your application code, a missing environment variable, a failing database connection string, or a permission problem in IAM. Note down the function name, file path, or microservice that is throwing the exception so the next methods can focus on the correct part of the stack.

Method 2: Test the Backend Directly Behind the Load Balancer

If your direct call works but the load balancer front end still returns 500 status codes, inspect the Listener rules and Health check path for the target group. A wrong health check path that returns 500 or 404 will cause targets to flap between healthy and unhealthy, which leads to intermittent 500s for users during traffic spikes.

Warning: Never change listener ports or production health check paths without confirming the same configuration in your infrastructure as code templates, otherwise your next deployment may revert your fixes.

Method 3: Validate Environment Variables and IAM Permissions

After correcting missing variables or updating IAM policies, redeploy the task definition, restart the EC2 service, or publish a new Lambda version so the runtime picks up the new configuration. Then retest your application endpoint from the browser and watch CloudWatch again to confirm that the 500 errors have stopped.