Why MS Outlook 365 Keeps Crashing and Restarting?

Microsoft Outlook is a widely used email and productivity tool, offering users a seamless experience in managing their emails, calendars, and contacts. However, like any software, it is not immune to occasional glitches and issues. Outlook data file errors is one such common problem, which one has to face every now and then.

Similarly, another frustrating problem user encounters is the constant crashing and restarting of MS Outlook 365 or Outlook desktop. The cause of this is very unpredictable and it can happen due to any possible reasons. However, in this blog post, we will delve into the possible reasons behind this issue and explore some potential solutions.

Why MS Outlook 365 Keeps Crashing? Reasons and Resolution

There are many possible reasons for these frequent crashes however, out all it the size of your MS Outlook data file, which could be the most common one. So before exploring anything it is better to first compact the OST file or PST file and see if that makes any difference. If not, then consider the below listed points to see if that works:

Outdated Software:

One common reason for MS Outlook 365 crashes is outdated software. Ensure that both Outlook and your operating system are running the latest updates. Microsoft regularly releases patches and updates to address bugs and improve the overall stability of the application.

Corrupted Outlook Data Files:

Corrupted or damaged Outlook data files (PST or OST) can lead to crashes. These files store your emails, contacts, and other mailbox data. To troubleshoot this issue, use the built-in Inbox Repair Tool (ScanPST.exe) to scan and repair corrupted data files. If the inbox repair tool does not respond, you can repair it as well.

Conflicts with Add-ins:

Outlook allows users to install third-party add-ins to enhance functionality. However, these add-ins can sometimes conflict with each other or the Outlook application itself, leading to crashes. Disable unnecessary add-ins and enable them one by one to identify the culprit. Additionally, check for updates to ensure compatibility with the latest version of Outlook.

Large Mailbox Size:

A mailbox with an excessive amount of data can strain Outlook’s resources and cause it to crash. Regularly clean up your mailbox by archiving old emails and attachments or consider using online archiving features provided by your email server. This will help reduce the overall size of your mailbox and improve Outlook’s performance.

Hardware Acceleration:

Outlook uses hardware acceleration to improve graphics performance. However, on some systems, this feature can lead to crashes. Disable hardware acceleration in the Outlook settings and see if the problem persists.

Faulty Outlook Profile:

A corrupted or faulty Outlook profile can also be a culprit. Create a new Outlook profile and configure it with your email account to see if the crashes persist. If the issue is resolved, you can transfer your data to the new profile.

Virus or Malware:

Viruses or malware can interfere with Outlook’s normal functioning. Ensure that your computer has updated antivirus software and perform a full system scan to eliminate any potential threats.

Before you proceed to fix the issue of frequent crashes, it is advisable to turn an OST file backup into PST, so that in case of data loss you can always recover it from backup. Also, it is quite easy to migrate the PST file to other applications like Thunderbird, Apple Mail, Outlook for Mac etc. by converting the PST into MBOX or other formats.


While MS Outlook 365 is a powerful and feature-rich application, occasional crashes can be a source of frustration for users. By understanding the potential reasons behind the crashes and implementing the suggested solutions, users can enhance the stability of their Outlook experience.

Regularly updating software, managing data files, and addressing conflicts with add-ins are essential steps to keep MS Outlook 365 running smoothly. If problems persist, seeking assistance from Microsoft support or IT professionals may be necessary to diagnose and resolve more complex issues.

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