Microsoft Confirms Outlook for iOS Crashes on iPads Due to Feature Flag Update Error

Microsoft has confirmed a significant issue affecting Outlook for iOS users on iPad devices, where the application crashes or freezes immediately upon launch. The problem stems from a specific coding error introduced in version 5.2602.0 of the app.

The root cause is related to a recent change in how the app handles feature flag updates. According to Microsoft's incident report (tracked as EX1220516), the update was intended to refresh application tabs rather than restart them when feature flags change. However, the implementation contained an error that is causing the app to fail on startup for iPad users.

Immediate Workaround Available

While Microsoft has developed a fix for this bug, the solution is currently awaiting Apple's App Store review and release process, which may take up to 24 hours. In the meantime, affected users can employ a temporary workaround:

1. Enable Airplane Mode on the iPad
2. Launch Outlook for iOS
3. Once the app opens successfully, re-enable Wi-Fi and/or cellular data

This workaround prevents the app from attempting to fetch updated feature flags during the initial launch, allowing it to start properly.

Scope and Severity

Microsoft has classified this as a notable incident in the Microsoft 365 admin center, a designation typically reserved for critical service issues with significant user impact. While the company hasn't released specific numbers on how many users are affected, the incident tag suggests the issue is widespread enough to warrant immediate attention.

Broader Pattern of Recent Issues

This Outlook for iOS crash is part of a series of recent issues Microsoft has been addressing across its product ecosystem:

Windows Update Problems: Earlier this week, Microsoft shared a temporary workaround for users experiencing Outlook freezes after installing the January 2026 security updates on Windows 11, Windows 10, and multiple Windows Server platforms (including Windows Server 2025, Windows Server 2022, and Windows Server 2019).

Emergency Out-of-Band Updates: Over the weekend, Microsoft released emergency updates for Windows 10, Windows 11, and Windows Server to fix credential prompt failures that affected remote connection apps and prevented devices with Secure Launch enabled from shutting down or entering hibernation.

Exchange Online Access Issues: Microsoft is actively working to mitigate another known issue (EX1221742) that prevents Exchange Online customers in the United States, France, and the United Kingdom from accessing their email accounts via Outlook on the web.

Technical Context

Feature flags are a common software development technique used to enable or disable features without deploying new code. They allow developers to gradually roll out changes and quickly disable problematic features. However, as this incident demonstrates, improper handling of feature flag updates can cause application instability.

The specific error here—where a change meant to refresh tabs instead caused crashes—highlights the complexity of managing state transitions in mobile applications. When feature flags update, the application must carefully manage its internal state to avoid conflicts between the old and new configurations.

What Users Should Do

1. For affected iPad users: Use the Airplane Mode workaround until the fixed version (5.2602.1 or later) becomes available in the App Store.

2. Monitor Microsoft 365 Admin Center: Organizations should check the admin center for updates on this incident and related issues.

3. Consider update timing: For enterprise environments, this incident serves as a reminder to consider phased rollouts of application updates, especially for critical productivity tools like Outlook.

Related Recent Issues

The Microsoft 365 ecosystem has seen several notable issues recently:

• Exchange Online IMAP4 access: An outage blocked access to mailboxes via IMAP4
• Classic Outlook encryption bug: A separate bug prevented opening encrypted emails
• Exchange Online rate limiting: Microsoft canceled plans to rate limit bulk emails
• Mobile device access: Plans to block Outlook access for outdated mobile devices
• New Outlook compatibility: Issues with opening Excel attachments in the new Outlook interface

This pattern suggests that Microsoft's development and testing processes for cross-platform applications are facing significant challenges, particularly as they manage updates across multiple operating systems and device types simultaneously.

Best Practices for Enterprise IT

For IT administrators managing Outlook deployments:

1. Test updates in staging environments before broad deployment
2. Monitor Microsoft's release notes for known issues before updating
3. Have rollback procedures ready for critical applications
4. Communicate workarounds to users when issues arise
5. Consider alternative access methods (like webmail) during application outages

The Outlook for iOS crash incident, while disruptive, demonstrates Microsoft's relatively transparent approach to incident management by quickly acknowledging the issue and providing a workaround while working on a permanent fix. However, the frequency of recent issues across the Microsoft 365 ecosystem may warrant a review of their quality assurance processes, particularly for updates that affect multiple platforms simultaneously.