Microsoft 365 Error Codes

How to Fix AADSTS20012 Error Adding Exchange to iPhone

Rana Garcia Oct 10, 2026 869 views

Question details

The user needs to resolve an authentication error preventing them from successfully adding a Microsoft Exchange account to their iOS device.

How to Fix AADSTS20012 Error Adding Exchange to iPhone

Product: Outlook for iOS / Microsoft Exchange
Device & OS: iOS
Scenario: Setting up a corporate Exchange email account on an iPhone using WS-Federation sign-in.
Observed behavior: The sign-in message is rejected as invalid, malformed, or potentially dangerous, triggering the AADSTS20012 error code and halting the account setup process.

Before you start

Before reaching out to support, take a screenshot of the error screen so you have the exact request ID, correlation ID, and timestamp readily available.

Solution 1Recommended

Contact In-App Support for Outlook on iOS

Reach out directly to the Outlook for iOS support team using the built-in help feature to report and resolve federation sign-in issues.

Since this specific error involves how Outlook handles WS-Federation messages during setup, the dedicated in-app support team is best equipped to investigate the backend logs.

Access your profile

Open the Outlook for iOS app and tap your profile photo located in the upper-left corner of the screen.

Navigate to Help & Feedback

Select the question-mark icon at the bottom of the side menu to open the Help & Feedback section.

Contact Support

Tap on 'Contact Support' and describe the issue. Be sure to provide the request ID, correlation ID, timestamp, tenant information, and the full AADSTS20012 error message.

Provide Accurate Details: Providing the exact correlation ID and timestamp is crucial, as it allows Microsoft engineers to locate your specific failed sign-in attempt in their server logs.

Solution 2

Involve Your Organization's IT Administrator

If the issue stems from the organization's backend configuration, an IT or Exchange administrator must review the identity federation settings.

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Frequently Asked Questions

What does the AADSTS20012 error code mean?

This error code signifies that a WS-Federation sign-in message was rejected during authentication because it was invalid, malformed, or flagged as potentially dangerous by the server.

Where can I find the correlation ID and timestamp?

These diagnostic details are usually displayed directly on the screen when the AADSTS20012 error occurs. Taking a screenshot of this page is the easiest way to record them.

Can I fix the WS-Federation configuration myself?

No. Federation and sign-in configurations are managed at the organizational level. You will need to contact your company's Exchange or Identity Administrator to resolve backend misconfigurations.

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