Outlook Error Codes

How to Fix Outlook Mobile Sign-In Error Code 0

Maira Mehtab Sep 27, 2026 869 views

Question details

The user is unable to sign into the Outlook mobile app and receives error code 0 along with error tag 9hehw.

Product: Microsoft Outlook Mobile
Device & OS: not provided
Scenario: Signing into an email account on the Outlook mobile application.
Observed behavior: The sign-in fails, displaying error code 0, error tag 9hehw, along with a correlation ID and a timestamp.

Before you start

Before troubleshooting the mobile app, try signing into Outlook on the web to verify whether your account credentials are correct and active.

Solution 1Recommended

Enable Exchange ActiveSync in the Exchange Admin Center

If you are using a work or school account, Exchange ActiveSync must be enabled by your administrator to allow mobile access.

This solution requires administrator privileges. If you are an end-user, you will need to contact your organization's IT department to perform these steps on your behalf.

Access the Exchange admin center

Log into the Microsoft 365 Exchange admin center using administrator credentials.

Locate the user mailbox

Navigate to 'Recipients' in the left-hand menu and click on 'Mailboxes', then select the specific user mailbox experiencing the error.

Open email app settings

In the mailbox properties pane, click on 'Email apps and mobile devices' and select 'Manage email apps settings'.

Enable ActiveSync

Ensure the toggle for 'Exchange ActiveSync' is enabled, then save the changes to restore mobile sign-in capabilities.

Propagation Time: It may take a few minutes for the changes to propagate across the server before the user can successfully sign into the mobile app.

Solution 2

Provide Diagnostic Details to Microsoft Support

If Exchange ActiveSync is already enabled and the issue persists, diagnostic details must be escalated to support.

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Frequently Asked Questions

What does error tag 9hehw mean in Outlook Mobile?

This error tag typically indicates an authentication or synchronization block preventing the mobile app from communicating with the Exchange server, most commonly caused by disabled Exchange ActiveSync settings.

Can I fix error code 0 on my own if it's a work account?

Usually, no. If you are using a work, enterprise, or school account, you will likely need to contact your organization's IT administrator to modify your mailbox permissions in the admin center.

Why can I access Outlook on the web but not the mobile app?

Outlook on the web uses different access protocols. Your account may have web access enabled, while mobile access protocols like Exchange ActiveSync might be restricted by your organization's security policies.

Where do I find the correlation ID for the Outlook error?

The correlation ID is an alphanumeric string displayed directly on the sign-in error screen in the Outlook mobile app, alongside the timestamp and error code.

Microsoft Office Error Codes