It's not able to complete the upgrade due to the configuration error. How many service escalations do you have defined? You can de-activate th and re-activate to help pinpoint the error.
Error: Service escalation host name or description is NULL
Error: Could not register service escalation (config file '/usr/local/nagios/etc/serviceescalations.cfg', starting on line 1736)
If you cannot resolve the error, can you send over the current dump of the configuration database and we'll take a look?
You can go to Configure > Core Config Manager > Service Escalations:
- Select 250 from the Limit Results dropdown at the bottom
- Click the Check All link at top left
- Select Deactivate from With Checked dropdown and click Go