Agents cannot be installed on the Exchange server (4254536)

Agents cannot be installed on the Exchange server and the following warning pops up on the screen:

Cannot create a job with server [Server_name] because necessary configuration information is missing for the server.

Refreshing the server in Project Manager and re-adding the target Exchange organization does not help.

The EMWMigration.log file shows the following error:

aeEMWGUIShared::E2kEnumerator::LinkSystemAttendantToServer Warning: The System Attendant object not found for server: [Server_name]

System Attendant mailbox has not been added to SQL database for some reason. It might have been unavailable or missing during enumeration.

To resolve the issue, add System Attendant mailbox to SQL database manually, as follows:

1) Back up the SQL database.
2) Close Project Manager application.
3) Start ADSIEdit
4) Open Configuration partition and expand it down to Services | Microsoft Exchange | [Organization name] | Administrative Groups | [Administrative group name] | Servers | [Server name] | Microsoft System Attendant
5) Open the Properties of the System Attendant mailbox
6) Copy the value of the legacyExchangeDN of the System Attendant mailbox
7) Open SQL database
8) Open SERVER table and add the legacyExchangeDN of the System Attendant mailbox to USERNAME3 field.