at-spi2-core-udeb software package provides Assistive Technology Service Provider Interface (dbus core for d-i), you can install in your Ubuntu 16.04 LTS (Xenial Xerus) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install at-spi2-core-udeb
at-spi2-core-udeb is installed in your system.
Make ensure the at-spi2-core-udeb package were installed using the commands given below,
$ sudo dpkg-query -l | grep at-spi2-core-udeb *
You will get with at-spi2-core-udeb package name, version, architecture and description in a table
| Distro | Ubuntu 16 04 lts xenial xerus |
| Section | debian-installer udeb packages |
| Package | at-spi2-core-udeb |
| Version | 2.18.3-4ubuntu1 |
| Description | Assistive Technology Service Provider Interface (dbus core for d-i) |
| Sub Section | Debian-installer |