Get-MailboxCalendarSettings

An administrator asked: When we add any new meeting request we get this error "Resource has declined your meeting because it is recurring. You must book each meeting separately with this resource."
Is the resource mailbox configured to decline recurring meetings? You can check this using Outlook or with the Get-MailboxCalendarSettings cmdlet:

Get-MailboxCalendarSettings MeetingRoom_name |fl

Specifically, check the AutomateProcessing and AllowRecurringMeetings properties. AllowRecurringMeetings should be true if you want to allow users to book recurring meetings. Using AutoAccept means the resource will automatically accept or decline meetings.

AutomateProcessing : AutoAccept
AllowRecurringMeetings : True

Use the Set-MailboxCalendarSettings to change these properties.

If the property is set to True, you need to clean the free/busy cache using the /cleanfreebusy switch.

You can also use Outlook to check the AllowRecurringMeetings setting. Open the resource mailbox using Outlook. Go to Tools, Options, Calendar Options, Resource Scheduling and verify that "Automatically decline recurring meeting requests" is not checked.