Microsoft shares Registry workaround for 'Out of memory or system resources' Outlook crash

Microsoft has confirmed that Classic Outlook is crashing following an "out of memory or system resources" error message. This issue is happening when more than sixty emails are opened at the same time.

In a new support article, Microsoft says:

When you open more than sixty emails, and have them all open at the same time, Outlook may show one of the following errors and crash:

“Sorry, we’re having trouble opening this item. This could be temporary, but if you see it again you might want to restart Outlook. Out of memory or system resources. Close some windows or programs and try again.”

The company is investigating what exactly is causing this out-of-memory (OOM) bug. It could be some memory leak or something else, as sixty emails are very unlikely to fill up the memory buffer unless someone is still running a gigabyte of RAM.

While Microsoft investigates (it also investigates Classic Outlook hanging when copying text), it has offered a workaround for those who must have more than sixty emails open for their workflow. It involves going to the following Registry key and tweaking the value:

HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\WindowsNT\CurrentVersion\Windows\USERProcessHandleQuota

The company writes:

To work around the issue use either of the following workarounds:

1. Avoid opening more than sixty emails at the same time.
2. If you must have more than sixty emails open at the same time you can set the USERProcessHandleQuota as documented in this article, User Objects – Win32 apps. Increasing the process quota could lead to overall system instability because it enables all processes on the machine to have more user objects open at the same time, placing additional strain on the operating system.
   
   This value can be set to a number between 200 and 18,000. The default is 10000 Decimal also represented as 2710 Hexadecimal.

You can find the issue here on the official support article on Microsoft's website.