Generate encrypted access to application hosted on Tomcat server from outside the virtual machine by configuring it through Azure Gateway using Self Signed Certificate

Hi Yadav, Poorvasha

Greetings,

Welcome to the Microsoft Q&A Platform. Thank you for reaching out & I hope you are doing well.

To fix the missing intermediate certificate error in Azure Application Gateway for your Tomcat application, follow these general steps:

The intermediate certificate was not found

Message: The Intermediate certificate is missing from the certificate chain presented by the backend server. Ensure the certificate chain is complete and correctly ordered on the backend server.

Cause: The intermediate certificate(s) isn't installed in the certificate chain on the backend server.

Solution: An Intermediate certificate is used to sign the Leaf certificate and is thus needed to complete the chain. Check with your Certificate Authority (CA) for the necessary Intermediate certificate(s) and install them on your backend server. This chain must start with the Leaf Certificate, then the Intermediate certificate(s), and finally, the Root CA certificate. We recommend installing the complete chain on the backend server, including the Root CA certificate. For reference, look at the certificate chain example under Leaf must be topmost in chain.

Note: A self-signed certificate which is NOT a Certificate Authority also results in the same error. This is because application gateway considers such self-signed certificate as "Leaf" certificate and looks for its signing Intermediate certificate. You can follow this article to correctly generate a self-signed certificate.

These images show the difference between the self-signed certificates. Screenshot showing difference between self-signed certificates.

The leaf or server certificate was not found

Message: The Leaf certificate is missing from the certificate chain presented by the backend server. Ensure the chain is complete and correctly ordered on the backend server.

Cause: The Leaf (also known as Domain or Server) certificate is missing from the certificate chain on the backend server.

Solution: You can get the leaf certificate from your Certificate Authority (CA). Install this leaf certificate and all its signing certificates (Intermediate and Root CA certificates) on the backend server. This chain must start with the Leaf Certificate, then the Intermediate certificate(s), and finally, the Root CA certificate. We recommend installing the complete chain on the backend server, including the Root CA certificate. For reference, look at the certificate chain example under Leaf must be topmost in chain.

Refer: https://learn.microsoft.com/en-us/azure/application-gateway/application-gateway-backend-health-troubleshooting#:~:text=your%20application%20gateway.-,The,-intermediate%20certificate%20was

Hope this clarifies.

Thanks,

Ganesh

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