AWS APP RUNNER 404 possible ap-southeast-1 service level issue

Hello.

I checked the AWS health dashboard and didn't find any reports of any issues with ap-southeast-1.
At this point, it is difficult to determine whether AWS is slow to detect the problem or whether the problem is specific to your AWS account.
https://health.aws.amazon.com/health/status

For a simple test, try deploying another AppRunner. If you get the same error, I recommend contacting AWS Support via "Account and billing."
Contacting "Account and billing" is free of charge.
https://docs.aws.amazon.com/awssupport/latest/user/case-management.html

Hey, I’ve seen this pop up a few times on App Runner, and your logs match the classic scenario. You’re right—the app seems healthy, but App Runner is failing to route traffic and serving 404s on the public endpoint.

This often happens due to an incorrect or missing Host header or SNI, not necessarily because the app itself is broken.

**This is what I am assuming. App Runner uses the Host header (for HTTP) or SNI (for HTTPS) to route requests to your service.

If those headers don’t match what App Runner expects (the service’s internal domain, not your custom domain), you’ll get a 404 or “unable to route traffic” error

https://docs.aws.amazon.com/apprunner/latest/dg/request-route-404-troubleshoot.html?utm_source=chatgpt.com . To Check

1. Are you hitting the public App Runner URL directly?

curl -I -H "Host: your-app-id.apprunner.aws-region.amazonaws.com" https://your-app-id.apprunner.aws-region.amazonaws.com/

If that works, then it’s routing using the Host header.

2. Using a custom domain or CloudFront in front of App Runner?

     a) Make sure the Origin Request Policy is set to AllViewerExceptHostHeader.
   
     b) That ensures App Runner sees its own domain in Host/SNI, not the custom URL (https://www.reddit.com/r/aws/comments/1ejofm2/404_from_cloudfront_with_apprunner_as_an_origin/?utm_source=chatgpt.com)
   

3. Private URL working fine? Good sign! a) If the private URL works and public URL doesn’t, it's almost always a Host/SNI mismatch.

Next STeps If hitting directly → set proper Host/SNI header. If using CloudFront or custom domain → switch to AllViewerExceptHostHeader. Redeploy after checking that your domain config matches App Runner’s expectations.

same as me, why is this happening, no changes to anything, but apprunner not working for few hours then back on. why?

Based on the symptoms you're describing, there could be several potential causes for your AWS App Runner service returning 404 errors and failing to deploy in the ap-southeast-1 region.

This could potentially be an account-specific issue rather than a regional service disruption. In similar cases, users have reported that their App Runner deployments failed repeatedly despite proper configuration, and the solution was an "account refresh" performed by AWS Support. According to reports, this happens when certain quotas related to App Runner service become restricted for an AWS account based on usage patterns, preventing App Runner instances from launching properly.

Here are some troubleshooting steps you can take:

1. Check your application logs in the App Runner console to see if there are any specific error messages that might explain the 404 errors.

2. Verify that your health check configuration is correct - while you mentioned health checks are successful, there might be a mismatch between the health check path and your actual application routes.

3. Try deploying a simple test application to see if the issue is specific to your application or affects any deployment in your account.

4. If you're using a VPC connector, verify that your network configuration is correct, including security groups and subnet settings.

5. Try deploying in a different region to determine if this is region-specific.

6. If all else fails, contact AWS Support. They may need to perform an "account refresh" to resolve quota-related restrictions that could be preventing your App Runner service from functioning properly.

The fact that metrics show no activity coinciding with the 404 errors suggests that traffic might not be reaching your application at all, which aligns with deployment failures and routing issues.
Sources
AWS App Runner not passing health check for a simple python application | AWS re:Post
AWS App Runner Failing to List Services | AWS re:Post
Rebuilding a failed App Runner service - AWS App Runner

It seems the issue starts at 9 AM same as @hamiltonchua

here's mine.