Knowledge Base

Troubleshooting migration problems caused by conflict with Outlook


When connected to a source Exchange server via the MAPI protocol, you are unable to continue the migration after installing the Office suite that includes Outlook. You receive the following or similar error message:

Migration process has been terminated. System.ServiceModel.FaultException: Unable to access mailbox: '<mailbox_name>'


CodeTwo migration software cannot be used on a machine where another program is installed that uses MAPI profiles, such as Outlook. This causes a conflict between the two programs as they both try to access these profiles.

Follow the steps below to be able to proceed with your migration on the same machine:

  1. Completely uninstall the Office suite with the uninstall support tool from Microsoft.
  2. Uninstall MAPI Client and Collaboration Data Objects (CDO) and your CodeTwo migration software from the Control Panel.
  3. Reinstall CodeTwo migration software along with the MAPI CDO. The latter can be installed by the CodeTwo installation wizard.


    When uninstalling CodeTwo migration software, the program's cache file and all user-defined job settings are retained in the installation folder.

    The default installation directories are:

    • for CodeTwo Exchange Migration:
      %ProgramFiles(x86)%\CodeTwo\Exchange Migration
    • for CodeTwo Office 365 Migration:
      %ProgramFiles(x86)%\CodeTwo\Office 365 Migration

    To be able to use the retained cache and job settings, you need to install the same version of CodeTwo migration software used until this point. Using a different version will cause this data to be overwritten.

    If you require support with the installation file, contact our Customer Success team

  1. Re-configure the source server connection. Learn more
  2. Start the migration job.

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