Error updating to version 3.1.4

When updating to the recent 3.1.4 update on our self-hosted on Ubuntu 22.04 server, it gets to 80% & generates an error listed as the following:
The command php artisan update:finish core 1 3.1.4 3.1.4 failed.
Exit Code: 1(General error)
Working directory: /var/www/akaunting
Output:
================
Finishing update...
In HtmlRenderer.php line 32:
Class DOMDocument not found

What seems to be missing??