Failed to find an exchange connection for selected mailbox

Problem:

The program is unable to migrate your mailboxes and you are receiving the following error during the migration:

Failed to find an exchange connection for selected mailbox.

Solution:

This error may be caused by the following reasons:

1. Corrupted installation
   Perhaps your installation got corrupted due to some disk failures or you have moved the software to another server, but some files are missing. In this case please remove the defined connections and add them again.
2. Invalid permissions
   Check if the CodeTwo folders under %programdata% directory are not set as read-only. Moreover, verify if the user running the migration has all necessary rights.
3. Changed DNS settings
   It may also happen that you have introduced some changes into DNS settings of your domain, so it points to a different server. Please consult this article to restore proper settings.