While creating or modifying Room mailboxes with Resource In Policy Request/Resource Out Policy Request, you get these errors: 'The values is already present in the collection' or ' The parameter 'legacyExchangeDN must be a non-empty string'.

While creating or modifying Room mailboxes with Resource In Policy Request/Resource Out Policy Request, you get these errors: 'The values is already present in the collection' or ' The parameter 'legacyExchangeDN must be a non-empty string'.

Possible Reason:

 

These errors would occur if the mailboxes selected for the Resource In Policy Request/Resource Out Policy Request policies are legacy mailboxes.

 

Solution:

 

Please remove legacy mailboxes from the selected list, and perform the operation again.

 

Please refer to the screenshot attached below.