Check if the below is applicable in your case:
Description: The health checks didn't return an expected HTTP code.
- Success codes are the HTTP codes to use when checking for a successful response from a target. You can specify values or ranges of values between 200 and 499.
The default value is 200. Check your load balancer health check configuration to verify which success codes that it's expecting to receive. Then, inspect your web server access logs to see if the expected success codes are being returned. Modify the success code value if necessary.
- Verify that the ping path is valid. The ping path is the destination on the targets for health checks. Be sure to specify a valid URI (/path?query). The default is /. Modify the ping path value if necessary.
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