Accessing Internal Web Server via Azure Application Proxy with Power Automate and Postman

Question

Accessing Internal Web Server via Azure Application Proxy with Power Automate and Postman

Fritz, Pascal 20

Hello,

Requirement: I need to access an internal web server that serves a static HTML page. The access is routed through the Azure Application Proxy. In a later step, I plan to send API calls to this internal web server using Power Automate.

Current Situation:

Accessing the internal web server via a browser using the external ___domain of the Azure Application Proxy works perfectly, and authentication is handled without any issues.
However, when I try to fetch the HTML page using a GET request in Postman with a Bearer Token, I always receive the error message: "Sign in to your account".

Note: internal

My initial goal is simply to successfully retrieve the static HTML page via Postman before moving on to API calls.

Problem: I’ve been stuck on this issue for days and haven’t been able to find a solution. I’ve already verified that the Bearer Token is correct and tried various approaches, but none have worked so far.

Question: Has anyone encountered a similar scenario or has any ideas on how to properly configure access via Postman? Are there specific settings or steps I need to follow to use the Azure Application Proxy in combination with Postman and later Power Automate?

Thank you in advance for your support!

browser

Postman

Khadeer Ali 5,815 Reputation points Microsoft External Staff Moderator

2025-06-04T12:50:17.62+00:00

@Fritz, Pascal ,

Thanks for reaching out. To better understand the issue and assist you effectively, could you please help with a few quick details:

What exact URL are you trying to call from Postman?

How are you generating the Bearer token you're using?

Is the internal app protected by Azure AD or does it have its own login as well?

Have you tried the same call using any other tool or method?
Fritz, Pascal 20 Reputation points

2025-06-04T13:06:43.3033333+00:00
Hi,

The exact url is darchivelcmessproxy.mycompanydomain.com

I generate the Token via the Authorization-Part in Postman. There i user Auth Type "OAuth 2.0" and Generate a new Token there.

To Access the html-site in the internal app, there is no protection. Only the APIs behind, have its own login with Username and Password. But for that, we will try to setup the openid-authentication in the app later

I only tried to access to the url with the Webbrowser and this is works fine. It shows the Microsoft Authentiaction, and after successfull authentication i will be redirected to the internal site
Khadeer Ali 5,815 Reputation points Microsoft External Staff Moderator

2025-06-09T10:15:03.77+00:00

@Fritz, Pascal

I wanted to check in and see if my earlier response addressed your question. If you still need assistance or have additional questions, feel free to reach out.
Khadeer Ali 5,815 Reputation points Microsoft External Staff Moderator

2025-06-10T09:30:41.2833333+00:00

@Fritz, Pascal

Just checking again to see if my earlier response answered your question. If you need more help or have any other questions, just let me know!

Accepted answer

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Your answer

Khadeer Ali 5,815 Reputation points Microsoft External Staff Moderator

2025-06-04T12:50:17.62+00:00

@Fritz, Pascal ,

Thanks for reaching out. To better understand the issue and assist you effectively, could you please help with a few quick details:

What exact URL are you trying to call from Postman?

How are you generating the Bearer token you're using?

Is the internal app protected by Azure AD or does it have its own login as well?

Have you tried the same call using any other tool or method?
Fritz, Pascal 20 Reputation points

2025-06-04T13:06:43.3033333+00:00

Hi,

The exact url is darchivelcmessproxy.mycompanydomain.com

I generate the Token via the Authorization-Part in Postman. There i user Auth Type "OAuth 2.0" and Generate a new Token there.

To Access the html-site in the internal app, there is no protection. Only the APIs behind, have its own login with Username and Password. But for that, we will try to setup the openid-authentication in the app later

I only tried to access to the url with the Webbrowser and this is works fine. It shows the Microsoft Authentiaction, and after successfull authentication i will be redirected to the internal site
Khadeer Ali 5,815 Reputation points Microsoft External Staff Moderator

2025-06-09T10:15:03.77+00:00

@Fritz, Pascal

I wanted to check in and see if my earlier response addressed your question. If you still need assistance or have additional questions, feel free to reach out.
Khadeer Ali 5,815 Reputation points Microsoft External Staff Moderator

2025-06-10T09:30:41.2833333+00:00

@Fritz, Pascal

Just checking again to see if my earlier response answered your question. If you need more help or have any other questions, just let me know!

Answer 1

@Fritz, Pascal ,

Thanks for the detailed info — that really helps clarify the situation.

Since the HTML site currently doesn’t have its own protection but is behind Azure Application Proxy with Azure AD pre-authentication, the key point is that Postman doesn’t support the interactive login flow that browsers do. That’s why you're getting the “Sign in to your account” message even with a token.

For now, access via browser is the best option for the HTML page since it handles Azure AD authentication automatically.
For Postman or Power Automate to work: Once OpenID authentication is set up on the APIs, we can use Client Credentials flow to get a token that works without user interaction. That will make automated access much smoother and avoid the current login issue.

Hope this helps. Do let us know if you have any further queries.

If this answers your query, do click Accept Answer and Yes for "Was this answer helpful." And if you have any further questions, let us know.

Fritz, Pascal 20 Reputation points

2025-06-11T06:55:17.7466667+00:00

Thank you for your support.
We will try, to setup the OpenID authentication.
I will come back to you, if we have some trouble.

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Accessing Internal Web Server via Azure Application Proxy with Power Automate and Postman

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