Remove CD-ROM from apt-get repositories in Debian 8
You need remove or comment the reference to the CD/DVD from the /etc/apt/sources.list
example: # deb cdrom:[Debian GNU/Linux 8.2.0 _Jessie_ – Official amd64 DVD Binary-1 20150906-11:13]/ jessie contrib main
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sudo nano /etc/apt/sources.list
And comment out the reference to the CD/DVD