How to Fix Unauthorized Client Error in SharePoint iPhone App
Question details
Users are unable to access company files on the SharePoint iPhone app due to an 'unauthorized_client' error, specifically occurring when the app attempts to authenticate via Microsoft Authenticator.
- Product
- Microsoft SharePoint App
- Device & OS
- iOS
- Scenario
- Attempting to log into a corporate Microsoft 365 account via the SharePoint mobile app to access company files.
- Observed behavior
- The SharePoint app displays an 'unauthorized_client' error or shows empty company files after switching to Microsoft Authenticator, despite the account working normally in Safari and on other devices.
Ensure your iPhone's operating system is fully updated and verify that you can successfully log into your SharePoint account using a standard mobile browser like Safari to confirm your credentials are correct.
Update SharePoint and Microsoft Authenticator
Outdated application versions frequently cause authentication token exchange failures between SharePoint and Microsoft Authenticator.
Navigate to the App Store on your iPhone and use the search tab to find both 'SharePoint' and 'Microsoft Authenticator'.
Tap the 'Update' button next to both applications if available to ensure you are running the latest software versions.
Swipe up from the bottom of your screen (or double-click the home button) to open the app switcher, then swipe up on both SharePoint and Authenticator to close them completely.
Re-open the SharePoint app on your iPhone and attempt to sign in with your corporate credentials to see if the error is resolved.
Contact Your Microsoft 365 IT Administrator
If local troubleshooting fails, the issue may be related to your organization's Azure Active Directory settings or conditional access policies.
Manage Your Office Documents Seamlessly with WPS Office
If Microsoft 365 mobile apps are giving you login trouble, consider using WPS Office to access, edit, and manage your local or cloud-based documents. It is a highly compatible and lightweight alternative for your mobile device.
- 1. Download the App: Search for WPS Office in the App Store and download the free application to your device.
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Frequently Asked Questions
Why does SharePoint work in Safari but not the iPhone app?
The SharePoint mobile app uses different authentication protocols, often relying on secure token handoffs with the Microsoft Authenticator app. If this handoff fails or is blocked by mobile-specific corporate security policies, you will receive an error. Safari, however, relies on standard web-based cookie authentication which bypasses these app-specific requirements.
Will reinstalling the SharePoint app fix the unauthorized client error?
Uninstalling and reinstalling the app can help by clearing corrupted cache data that might be causing the login loop. However, you should also ensure the Microsoft Authenticator app is updated, as the issue frequently originates from the communication breakdown between the two apps.
What if only one user in the company experiences this SharePoint login error?
If the issue is isolated to a single user, it usually indicates a device-specific problem, such as an outdated Authenticator app, a corrupted login token on that specific iPhone, or a newly enforced conditional access policy targeting that specific user's device state.
