Outlook unexpectedly prompts to reopen items from your last session

Last Updated: September 28, 2023

ISSUE

When starting Outlook Desktop, you are unexpectedly prompted with the dialog “Outlook closed while you had items open. Reopen those items from your last session?”

Outlook last session error

This behavior may happen if you are using an Office perpetual retail SKU such as Microsoft Office Professional Plus and Office Home and Business starting with Version 2306 (Build 16529.20154).

In most cases with Office perpetual the Outlook Options do not show this feature so you cannot set it in the user interface. To check for the option, use the following steps:

Select File, then Options.
In the General tab, under Start up options, select Ask me if I want to restore previous items from the drop-down menu.

Outlook Start up options

This feature is further documented here, Automatically restore windows in Outlook.

STATUS: FIXED

This issue is fixed in Version 2309 Build 16827.20130. To install the update immediately select File > Office Account > Update Options > Update Now.

WORKAROUND

If the option does not appear in the Outlook Options and you want to disable it, you can set a registry key for the setting as a workaround. Since the feature recurrently appears and disappears, this might or might not stop all occurrences of the problem. So, this might not be a comprehensive solution.

The registry key is:

HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Preferences
DWORD: ReopenWindowsOption
Value: 1

The setting maps to the following registry values:

Never reopen previous items = 1
Ask me if I want to reopen items = 0
Always reopen previous items = 2

Steps to add the preference registry key to tell Outlook to never reopen previous items:

Start Registry Editor.
Create or edit the following DWORD registry value at the specified location.

Subkey: HKEY_CURRENT_USER\Software\Microsoft\Office\16.0\Outlook\Preferences
DWORD: ReopenWindowsOption
Value: 1
Exit Registry Editor.
Restart Outlook.