(Entra Application Proxy Error) Private Network settings: Application operation failed

Question

Can anyone offer any suggestions on how I can get some additional information as to why I am receiving this error when attempting to configure an Enterprise Application to use on-premises Entra Application proxy?

I was initially having issues getting App Proxy to work at all, and I eventually found a link to an App proxy FAQ that stated you need to use your original .onmicrosoft.com domain with App Proxy. It just so happens that I was was using a different .onmicrosoft.com as my fallback from the one I initially setup with the tenant. So I changed it back to the original, but now I get this error whenever I try to create an App Proxy URL in an Enterprise app. And now I get the error regardless of the .onmicrosoft.com domain I'm using as my fallback.

I was just curious if there were some additional methods of debugging this. I'm not seeing anything obvious in the Event logs on the machines hosting the connecters, and there isn't anything revealing (to me) in the Entra audit logs.

Answer 1

Hello @Mecken Swyter,

Thank you for posting your query on Microsoft Q&A.

Based on your description, it seems you're encountering the error "Private Network settings: Application operation failed" while creating an on-premises application proxy in Entra ID. You mentioned that you have replaced the initial onmicrosoft.com fallback domain of your tenant in Microsoft 365.

Yes, your understanding of the issue as described in the App Proxy FAQ document is correct. You can refer to the document here:

Microsoft Entra Application Proxy FAQ

As you stated, I understand that you've reverted to the original fallback domain, but the error persists when configuring an App Proxy application. Please let me know if this understanding is incorrect.

To resolve this issue:

1. Ensure that you are using the original fallback domain.
2. Navigate to Microsoft Entra ID > Application Proxy > Configure an app.
3. Expand the External URL domain list and select your initial onmicrosoft.com domain from the options. Avoid selecting any domain that includes xxxx.msappproxy.net.

I hope this information is helpful. Please feel free to reach out if you have any further questions.

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Thanks,
Raja Pothuraju.