Out of Memory or System Resources – Fix This Outlook Error

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  • Published on
    March 26th, 2020
  • Updated on
    December 22, 2021
  • Read Time
    7 minutes
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Have you ever received an Outlook error message like – Out of memory or system resources? It is really very annoying when you receive an error message from the application that you use daily. In this article, we will discuss one of the most common Outlook error messages that may occur due to various reasons. I will also share the useful tips to fix the Outlook error – Out of memory or system resources.

Outlook Error – Out of Memory or System Resources

The Microsoft Outlook out of memory or system resources error can occur in any version of Microsoft Outlook when you try to open the Outlook application.

Out of Memory

The above Outlook error most possibly occurs if there are too many PST files connected to your Outlook profile and the files are fairly large. In case you do not know, Microsoft Outlook has a limited amount of space for each of the email accounts you have configured with it. This means whenever you open an Outlook data file, Microsoft Outlook uses a certain part of memory as a cache in order to improve its performance. And when space reaches its limit and there is no free space left for Outlook to use, the “Outlook out of memory or system resources” error pops up. In some cases, corruption in PST files can also cause this Outlook error.

How to Fix “Outlook Out of Memory or System Resources” Error?

Now let us discuss the ways to fix this Outlook error. There are multiple solutions using which you can fix this Outlook error. I have given the best possible solutions below, you should try them one by one.

Reduce the Number of PST Files

Since the primary reason for this Outlook error is a large number of PST files connected to your Outlook profile, you can simply resolve this error by reducing the number of PST files. Disconnect the PST files that are not being actively used by Microsoft Outlook at a point in time. There are two ways to do that:

outlook full

Way #1: First, open Microsoft Outlook. Then right-click the PST file that you want to close, and select Close in the popup context menu. This will close the PST file. In the same way, you can close other PST files one by one.

outlook storage error

Way #2: First, open Microsoft Outlook. Click the File tab on the taskbar >Account Settings. On the Account Settings dialog box, click the Data Files tab. Now click the PST file once and then click the Remove button to remove it. In the same way, you can remove other PST files one by one.

Read here: How to Open PST file without Outlook? – Challenges & Solution

Note: If you do not want to remove the PST files from Outlook but want to fix the Outlook error, you should try the next solution.

Reduce the Memory Cache Size

Instead of removing the PST files from your Outlook profile, you can reduce the memory cache size assigned by Outlook to each PST file using the Registry. You need to follow the steps given below:

Step 1: First, make sure Microsoft Outlook is closed. Go to the Start menu by clicking the Win key.

Step 2: Then type “regedit” in the search box, and hit the Enter button. This will open the Registry Editor window.

Step 3: In the registry editor, you need to browse to the key given below:


Step 4: Now right-click PST and then select New>DWORD Value. Note: You need to select the value as per your Outlook version, i.e. for Outlook 32-bit and 64-bit, select DWORD (32-bit) Value and QWORD (64-bit) Value respectively.

outlook storage full

Step 5: You need to name this new value that you are creating – UseLegacyCacheSize. Then double-click it and define its value data as 1.

Step 6: Now close Registry Editor and restart Microsoft Outlook on your computer.

Note: Keep in mind that using the above solution will decrease the Outlook’s performance because now only a few read/write operations will be cached.

By reducing the number of PST files and/or by reducing the memory cache size, you can successfully fix the Outlook out of memory or system resources error. Now you can open Outlook without any error message. But if still the same Outlook error occurs, this means the PST file you are trying to add is corrupted and you need to repair it. To learn how to repair PST file, please refer to solution #3.

Repair PST File

There are two ways to repair PST file – either you can use the Inbox Repair tool aka scanpst utility, or you can use a professional PST Repair tool. Before you can use any paid solution, you should try the Inbox Repair tool provided by Microsoft itself. Comes as a built-in tool in Outlook, the scanpst utility can scan corrupt PST file and repair it. You can find the scanpst utility exe under the installation directory of your Outlook application. Double-click it and then follow the steps given below to repair PST file using the scanpst utility:

Step 1: On the Microsoft Outlook Inbox Repair Tool window, click the Browse button and select the corrupt PST file that you want to repair.

Step 2: Once you select the PST file, it will be shown in the edit box. Now click the Start button to start the scanning process.

inbox repair tool

Step 3: The scanning process is being conducted on your computer. It may take some time so do not cancel the process.

inbox repair utility

Step 4: Once the scanning process is successfully completed, you will see the report in which the total number of errors/issues are given.

Step 5: Now you can start the repairing process by clicking the Repair button. Note: There is an option to take the backup of your PST file.

Within a few minutes, the PST file will be repaired.

pst recovery

You can then try to add this repaired PST file in your Outlook profile. In case you are still receiving the same Outlook error, you should consider using a professional PST Repair tool to repair PST file.

Professional PST Repair Tool

Although the Inbox Repair tool is quite effective, it may fail sometimes if the PST files are severely corrupted. In such a situation, you should use a professional PST Repair tool. Download the Outlook PST Repair tool provided by SysInfo. This software is highly capable of fixing severely corrupted PST files and restoring maximum mailbox data from them. Just have a look at the key features of this PST Repair tool –

  • It allows you to recover the complete mailbox data that include emails, attachments, contacts, calendar, etc. from the corrupt PST file.
  • This tool can repair PST file of any size. There is no such size limitation. A PST file up to 80 GB has been successfully tested.
  • During scanning and recovery processes, it maintains the original folder hierarchy of the Outlook PST files.
  • If the PST files are encrypted and/or password protected, even then you can use this software to repair PST file.
  • Using this software, you can save the recovered mailbox data into a new file of PST and other email file formats that include MSG, MBOX, DBX, and EML.
  • It supports PST files created by all versions of Microsoft Outlook including the latest 2019.
  • This software smoothly runs in all Windows-based operating systems including the latest Win 10.
  • It is available with the demo version for free evaluation. Demo version will show you the preview of your PST file mailbox data.

Please check the working of software:


The article has explained Outlook out of memory or system resources error in detail. There are multiple solutions given here in this article that will you fix the Outlook error. You should try the given solutions one by one. In case the manual solutions do not work, you should use a professional solution. I have suggested a PST Repair tool, highly recommended by many Outlook users and professionals.

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