I'm using an Azure Application Gateway v2 to route traffic to a backendpool containing VMs running some docker container hosting an aspnet core webapi. The application is listeing in port 443.
The gateway listener is configured to accept HTTPS connections. A pfx certificate has also been added.
The HTTP setting of the gateway is configured as follow:
I've provided, hopefully, the correct root certificate for the setting. I've exported the certifacte as described here: https://docs.microsoft.com/de-de/azure/application-gateway/certificates-for-backend-authentication
All VMs from the backend pool use the same certificate as the gateway listener.
When calling the api using a C# application or open a specific url within a browser, the connections seems to be trusted.
But I get an error when calling the api using postman with endabled SSL cerificate verification. Error: unable to verify the first certificate
A check on sslhopper.com also indicates an issue within the chain.
I got further information doing a chekc on digicert.com.
TLS Certificate is not trusted The certificate is not signed by a trusted authority (checking against Mozilla's root store). If you bought the certificate from a trusted authority, you probably just need to install one or more Intermediate certificates. Contact your certificate provider for assistance doing this for your server platform.
I'm really stuck in resolving the issue. All helpful hints are very welcome. The production environment, running on a Windows Server, wihtout the Gateway but the same certificates is valid. So the issue must be somewhere in the gateway configuration.
