Resolve Outlook POP and PST Issues by Uninstalling Windows 11 KB5074109 Update

If you’re experiencing freezes or hangs with Outlook Classic while using POP accounts or managing PST files, you may need to uninstall the Windows 11 update KB5074109 or switch to webmail. Additionally, third-party applications that save files to cloud storage solutions like OneDrive can also become unresponsive, as both issues appear to stem from a common underlying problem.

It’s uncommon for Microsoft to acknowledge its errors, yet the January 2026 Update has proven problematic, disrupting key features in Windows 11, including Sleep mode (S3) on older machines. Testing by Windows Latest revealed several shortcomings from this update, such as black screens, loss of custom desktop backgrounds, and issues with File Explorer’s customization settings.

Initially rolled out on January 13, 2026, the mandatory KB5074109 update was automatically installed on many PCs. However, users soon observed that Outlook Classic was rendered inoperative, preventing access to emails. Notably, this issue only affects the traditional Outlook Classic application, leaving the web-based Outlook operational.

Outlook hangs after Windows 11 KB5074109

Windows Latest identified the issue as stemming from the use of POP accounts configured in Outlook Classic for Windows 11. Many users, including myself, rely on the Post Office Protocol (POP) to access emails offline and consolidate multiple accounts into a single inbox.

Moreover, Outlook is prone to crashing on Windows 11 25H2 when PST files are synced with OneDrive. For those who are unfamiliar, PST (Personal Storage Table) files store crucial Outlook information such as emails, Sent Items, drafts, calendars, and contacts directly on your local device.

According to a support document spotted by Windows Latest, Microsoft has acknowledged the issue impacting Outlook and stated that existing workarounds are complicated. Consequently, users are encouraged to utilize webmail in the interim. If webmail usage is not a viable option, uninstalling KB5074109 becomes necessary.

“Until a resolution is provided, we recommend using webmail. The alternative workarounds might be cumbersome, ” Microsoft clarified. Suggested workarounds include “moving PST files outside of OneDrive, ” a process that is not straightforward or “removing the Windows Update.” These are valid alternatives if Outlook has become unusable on Windows 11.

It’s important to be cautious, as uninstalling Windows updates can expose your system to security vulnerabilities. For instance, the January 2026 Update addressed over 100 security flaws.

Understanding the Outlook Classic Issues from Windows 11 KB5074109

With POP accounts, Outlook stores data directly into the PST file. However, if that PST file resides within a OneDrive-synced folder, OneDrive’s synchronization engine may lock the file during uploads or scans.

This means that when you exit Outlook, and it attempts to save Sent Items back to the PST, OneDrive could maintain a lock or an open connection. Consequently, Outlook is unable to close down properly and may remain running in the background indefinitely.

Microsoft has confirmed that KB5074109 not only crashes Outlook but also affects the ‘Sent Items’ folder, leading to missing sent emails. Users often find Outlook stalling at “Not Responding, ”necessitating either the termination of the Outlook.exe process or a system reboot each time they launch Outlook.

Possible Unresponsiveness of Other Apps Post-January 2026 Update

In a separate updated support document, Microsoft quietly acknowledged that some applications may become unresponsive or encounter errors. This can prevent users from effectively saving or opening files stored in OneDrive or Dropbox.

“If you are experiencing this issue, please reach out to the application developer for potential alternative file access methods, ” Microsoft stated. They assured customers that they are actively devising a resolution and will provide updates as more information becomes available.

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