DominoFreeBusyService.exe crashes with System.AccessViolationException when querying Free/Busy in CMN 3.10 (4381536)

When querying Free/Busy data from Exchange to Domino (either via Outlook or using the PowerShell cmdlet Get-CmnDominoFreeBusy), the DominoFreeBusyService.exe crashes.

The Windows Application Event Log shows Event ID 1026 with the following error details:

Application: DominoFreeBusyService.exe
Framework Version: v4.0.30319
Description: The process was terminated due to an unhandled exception.
Exception Info: System.AccessViolationException
at <Module>.NAMELookup2(SByte*, UInt32, UInt16, SByte*, UInt16, SByte*, UInt16, SByte*, Void**)
at CMN.API.FreeBusy.DominoLibrary2.NameRepository.GetTargetDominoUsers(...)
at CMN.API.FreeBusy.DominoFreeBusy.DominoUserMapRepository.GetDominoUserMap(...)
at CMN.API.FreeBusy.DominoFreeBusy.DominoFreeBusyConnector.GetFreeBusyInfo(...)

This is a known issue (ID 541327) in Coexistence Manager for Notes 3.10.

The 64-bit version of the CMN Free/Busy Connector cannot correctly process Free/Busy requests sent from Exchange to Domino. This limitation results in an access violation crash when the service attempts to query the Domino environment.

To resolve this issue, the CMN Free/Busy Connector server must be switched to the 32-bit architecture. The backend Domino servers can remain on 64-bit versions.

Perform the following steps on the server hosting the CMN Free/Busy Connector:

1. Uninstall the 64-bit HCL Notes Client.

2. Uninstall the 64-bit CMN Free/Busy Connector.

3. Install the 32-bit HCL Notes Client.

4. Install the 32-bit CMN Free/Busy Connector.

5. Configure the 32-bit Connector to point to your existing Domino environment.

6. Restart the CMN services.

Once the 32-bit components are in place, Free/Busy queries from Exchange to Domino will function correctly.