How to Fix Outlook Out of Memory or System Resources Error

This guide walks you through the most effective ways to resolve the “Out of Memory or System Resources” error in Microsoft Outlook. This error typically appears when Outlook cannot allocate enough memory or system resources to function properly, often due to a corrupted profile, excessive add-ins, or a bloated data file. The steps below are ordered from quick fixes to more thorough solutions, and you can stop once the issue is resolved.

What You’ll Need

Administrator access to your Windows computer (for some steps)
Your Outlook password (if you need to recreate your profile)
Approximately 15–30 minutes of time

Step-by-Step

Close Outlook and restart your computer. This clears temporary memory issues. If the error only happens occasionally, a simple restart may be all you need. After restarting, open Outlook and see if the error persists.
Run Outlook in Safe Mode. Safe Mode starts Outlook without add-ins, which are a common cause of resource exhaustion. Press Windows + R, type outlook.exe /safe, and press Enter. If Outlook opens without the error, an add-in is likely the culprit.
Disable problematic add-ins. In Outlook, go to File > Options > Add-ins. At the bottom, select COM Add-ins from the “Manage” dropdown and click Go. Uncheck all add-ins, then click OK. Restart Outlook normally. If the error is gone, re-enable add-ins one by one to identify the offender. Once found, keep that add-in disabled or update it.
Repair your Outlook data file. A corrupted or oversized PST/OST file can cause memory errors. Close Outlook. Open Control Panel > Mail (or search for “Mail” in Windows). Click Data Files, select your account, and click Open File Location to note the path. Then close that window. Now run the Inbox Repair tool (Scanpst.exe). The default location is C:\Program Files\Microsoft Office\root\Office16\ (or similar). Open Scanpst.exe, browse to your data file, and click Start. Follow the prompts to repair. This can take a while for large files.
Compact your Outlook data file. Even after repair, a large data file can still cause memory pressure. In Outlook, go to File > Account Settings > Account Settings. Click the Data Files tab, select your account, and click Settings. Then click Compact Now. This reduces the file size and can improve performance.
Create a new Outlook profile. If the above steps fail, the profile itself may be corrupted. Go to Control Panel > Mail > Show Profiles. Click Add to create a new profile, name it (e.g., “NewProfile”), and enter your email settings. Then, under “When starting Microsoft Outlook,” select Prompt for a profile to be used and choose the new profile. You can delete the old profile later if everything works.
Update Office and Windows. Outdated software can have memory leaks that Microsoft has already fixed. Go to File > Office Account > Update Options > Update Now. Also, install Windows updates via Settings > Update & Security > Windows Update.
Increase virtual memory (if comfortable). If your system has low RAM, increasing the page file can help. Go to Settings > System > About > Advanced system settings. Under Performance, click Settings > Advanced > Change. Uncheck “Automatically manage paging file size,” select your drive, choose Custom size, and set Initial size to 1.5× your RAM and Maximum to 3× your RAM (e.g., 8 GB RAM → 12288 MB initial, 24576 MB max). Click Set and restart. Only do this if you understand the implications.

Common Mistakes

Skipping the restart. Many users jump straight to complex fixes, but a simple reboot resolves temporary resource issues in many cases.
Not backing up before repairing. The Inbox Repair tool can sometimes make changes that are hard to undo. Always back up your PST/OST file to another drive before running Scanpst.exe.
Disabling all add-ins permanently. You might lose functionality. Disable only to diagnose, then re-enable one by one.
Ignoring the data file size. A PST over 20 GB (or OST over 50 GB) is prone to errors. Archiving old emails is a better long-term solution than repeatedly repairing.
Creating a new profile without noting your old settings. You may lose custom signatures, rules, or server settings. Write them down first.

Tips

Archive regularly. Use AutoArchive (File > Options > Advanced > AutoArchive) to move old emails to a separate PST. This keeps your main file small.
Keep add-ins minimal. Only install add-ins you actually use. Each one consumes memory.
Close other memory-hungry apps. If you often have many programs open, Outlook may run out of resources. Close browsers or large applications when using Outlook.
Use the 64-bit version of Office. If you have 64-bit Windows, the 64-bit Outlook can handle larger data files and more memory. Check via File > Office Account > About Outlook.
Run a disk cleanup. Low disk space can contribute to resource issues. Use the built-in Disk Cleanup tool to free up space.

Troubleshooting

Error still appears in Safe Mode? If so, the problem is not an add-in. Move to the repair and profile steps.
Scanpst.exe cannot find your data file? Use the Data Files button in Control Panel > Mail to locate the exact path. It’s usually in %LocalAppData%\Microsoft\Outlook.
Repair tool reports errors but doesn’t fix them? Run it a second time. Sometimes multiple passes are needed. If it still fails, create a new profile and import your data from the old PST.
New profile works but you lose your emails? You can import the old PST: File > Open & Export > Import/Export > Import from another program or file > Outlook Data File (.pst). Select the old file and import.
Error occurs only when sending/receiving? This can indicate a server-side issue. Try removing and re-adding your email account, or check with your IT admin.
All else fails? Use the Microsoft Support and Recovery Assistant tool. It can automate many of these steps. Download it from Microsoft’s official site.

Frequently Asked Questions

Q: Will I lose my emails if I create a new profile?
A: No, your emails are stored in a PST or OST file. A new profile just changes how Outlook connects to that file. You can attach the existing data file to the new profile.

Q: How often should I compact my Outlook data file?
A: Only when you notice performance issues or after deleting a large number of items. Compacting too often is unnecessary, but doing it monthly can help if you receive many emails.

Q: Can I fix this error without admin rights?
A: Most steps (closing apps, disabling add-ins, compacting) don’t require admin. However, running Scanpst.exe or changing virtual memory may require admin access. If you don’t have it, contact your IT department.

Q: Does this error mean my computer is out of RAM?
A: Not necessarily. It often means Outlook has hit a limit within its own memory space, especially in 32-bit versions. Reducing add-ins and data file size usually helps more than adding RAM.

Q: Is there a way to prevent this error in the future?
A: Yes: keep your data file under 20 GB, limit add-ins, regularly archive, and keep Office updated. Also, consider using the 64-bit version if you have a large mailbox.

Q: Why does the error mention “system resources” specifically?
A: This is a Windows term for memory and internal system limits. Outlook can exhaust these resources when it has too many open handles, which often happens with many add-ins or a very large data file.

General steps for current mainstream versions; menus can differ by device and version. See the disclaimer or report an error.

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