AADSTS900971: No reply address provided. But it is provided

Question

AADSTS900971: No reply address provided. But it is provided

Polly Ruhnke 0

I am having this error message with app authentication; however, the redirect url in Azure and the one being requested are the same, so I am not sure how this is happening.

I am using msal and flask, if this means anything to anyone. Screenshot 2026-01-30 at 10.16.34 AM

Screenshot 2026-01-30 at 10.15.14 AM

Vinodh247 40,986 Reputation points MVP Volunteer Moderator

2026-02-01T10:07:45+00:00

Hi ,

Thanks for reaching out to Microsoft Q&A.

AADSTS900971 means Entra ID did not receive a redirect_uri in the authorize request that exactly matches one registered in the app. Even if it is configured in the portal, the value sent at runtime must match character-for-character (scheme, hostname, port, path, and trailing slash).

Common causes are: the app is calling /authorize without redirect_uri, the redirect URI is URL encoded incorrectly, a different port or hostname is used (for example localhost vs machine name), or the app is using a different platform type (SPA vs Web). Fix it by explicitly passing redirect_uri=http://localhost:8050/oauth2/callback in the auth request and ensure the same URI exists under Authentication --> Web in Entra ID.

Please 'Upvote'(Thumbs-up) and 'Accept' as answer if the reply was helpful. This will be benefitting other community members who face the same issue.
Sridevi Machavarapu 17,230 Reputation points Microsoft External Staff Moderator

2026-02-02T02:23:15.3533333+00:00

Hello Polly Ruhnke,

Please share more details like your current authentication flow, your python code by removing sensitive information to troubleshoot further.

Your answer

Vinodh247 40,986 Reputation points MVP Volunteer Moderator

2026-02-01T10:07:45+00:00

Hi ,

Thanks for reaching out to Microsoft Q&A.

AADSTS900971 means Entra ID did not receive a redirect_uri in the authorize request that exactly matches one registered in the app. Even if it is configured in the portal, the value sent at runtime must match character-for-character (scheme, hostname, port, path, and trailing slash).

Common causes are: the app is calling /authorize without redirect_uri, the redirect URI is URL encoded incorrectly, a different port or hostname is used (for example localhost vs machine name), or the app is using a different platform type (SPA vs Web). Fix it by explicitly passing redirect_uri=http://localhost:8050/oauth2/callback in the auth request and ensure the same URI exists under Authentication --> Web in Entra ID.

Please 'Upvote'(Thumbs-up) and 'Accept' as answer if the reply was helpful. This will be benefitting other community members who face the same issue.
Sridevi Machavarapu 17,230 Reputation points Microsoft External Staff Moderator

2026-02-02T02:23:15.3533333+00:00

Hello Polly Ruhnke,

Please share more details like your current authentication flow, your python code by removing sensitive information to troubleshoot further.

Share via

AADSTS900971: No reply address provided. But it is provided

Your answer