Outlook 2010: Error adding more than 30 calendars in the Calendar module

Here is a good to know information about the Outlook 2010 Calendar module.

If you got used to working with more than 30 calendars at the same time, then this blog will definitely help you further.

I know this limitation was not present under Outlook 2007, so this will help you, if you decided to upgrade to Outlook 2010.


In Outlook 2010, there is a default limit of thirty (30) calendars that can be displayed in the Calendar module at one time. If you try to enable more than 30 calendars, you receive the following error.


“More than 30 calendars cannot be viewed at once.”


To allow more than 30 calendars to be displayed at the same time in the Calendar module, configure the following registry data:


Key: HKCU\Software\Policies\Microsoft\Office\14.0\Outlook\Options\Calendar


Key: HKCU\Software\Microsoft\Office\14.0\Outlook\Options\Calendar

DWORD: CalendarMaximumNumber

Values: 40, 50, 60, 60, 70, 80, 90, or 100 (decimal)


Note: If you use any other value, it is ignored and the default limit of 30 calendars will be enforced.

Note: If you configure the limit to 40 calendars, for example, and you try to enable 41 calendars in the Calendar module, the error message displayed is updated to include the configured limit.

In this example, the error will be:


“More than 40 calendars cannot be viewed at once.”


I hope this is useful information for those who need this functionality.

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