Can't login account on Outlook App. Facing "An error occurred during authentication. Please try again later."

Question

We are experiencing an issue with logging into Exchange On Premises ( Exchange Server 2013/2019) email on the Outlook app for both Android and iOS. All users who are accessing their accounts for the first time or relogging after logging out are encountering the following error: "An error occurred during authentication. Please try again later." I would appreciate any assistance you can provide. Thank you! Please note:

This is NOT an internet connection issue.

This is NOT a credential issue.

This is NOT an app update issue

This is NOT Android or iOS issue.

This is NOT an issue with an outdated version.

Using two-factor authentication doesn't matter.

Answer 1

Hi @Yousuf Aziz ,

Welcome to the Microsoft Q&A platform!

Based on your description, you are experiencing authentication errors for Exchange On-Premises (Exchange Server 2013/2019) on Outlook apps for Android and iOS. Here are a few steps you can try to resolve:

1. Make sure your Autodiscover service is configured correctly. You can test your Autodiscover settings using the Microsoft Remote Connectivity Analyzer.
2. Make sure all necessary Exchange services are running. Sometimes, restarting IIS or Exchange services can resolve connectivity issues.
3. If you are using Basic Authentication, consider switching to Modern Authentication. Basic Authentication has been deprecated, and using Modern Authentication can resolve many issues related to mobile device connectivity.
4. Check if there are any mobile device policies that may affect the authentication process. Sometimes, policies may inadvertently block or restrict access.

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Please feel free to contact me for any updates. And if this helps, don't forget to mark it as an answer.

Best,

Jake Zhang