Identify and terminate the process using the port related to the error, then proceed with the installation of the Veeam software.
The following PowerShell script can be used to identify the process identifier number (PID) and process name using the specified port.
For environments where PowerShell has been disabled, the following command can be used to determine the PID of the process using the port.
The examples above are for the error "Selected Veeam Backup Catalog service port is not available." and assume the default port of 9393.