오류: 'mongodb' 패키지에 설치 후보가 없습니다.

apt-get 때문에 cloud9에 BeagleBone용 패키지를 설치할 수 없습니다 E: Package 'mongodb' has no installation candidate. 동일한 오류로 인해 어떤 패키지도 작동하지 않습니다. 업데이트하고, 업그레이드하고, 다시 시작했지만 아무것도 작동하지 않습니다.

내 BBG에 대한 추가 정보:

debian@beaglebone:/var/lib/cloud9$ uname -a
Linux beaglebone 4.9.82-ti-r102 #1 SMP PREEMPT Thu Feb 22 01:16:12 UTC 2018 armv7l GNU/Linux


debian@beaglebone:/var/lib/cloud9$ cat /etc/*-release
PRETTY_NAME="Debian GNU/Linux 9 (stretch)"
NAME="Debian GNU/Linux"
VERSION_ID="9"
VERSION="9 (stretch)"
ID=debian
HOME_URL="https://www.debian.org/"
SUPPORT_URL="https://www.debian.org/support"
BUG_REPORT_URL="https://bugs.debian.org/"

또한 내 source.list 파일은 다음과 같습니다.

GNU nano 2.7.4               File: /etc/apt/sources.list                                                                    

deb http://deb.debian.org/debian stretch main contrib non-free
#deb-src http://deb.debian.org/debian stretch main contrib non-free

deb http://deb.debian.org/debian stretch-updates main contrib non-free
#deb-src http://deb.debian.org/debian stretch-updates main contrib non-free

deb http://deb.debian.org/debian-security stretch/updates main contrib non-free
#deb-src http://deb.debian.org/debian-security stretch/updates main contrib non-free

#deb http://deb.debian.org/debian stretch-backports main contrib non-free
##deb-src http://deb.debian.org/debian stretch-backports main contrib non-free

#Kernel source (repos.rcn-ee.com) : https://github.com/RobertCNelson/linux-stable-rcn-ee
#
#git clone https://github.com/RobertCNelson/linux-stable-rcn-ee
#cd ./linux-stable-rcn-ee
#git checkout `uname -r` -b tmp
#
deb [arch=armhf] http://repos.rcn-ee.com/debian/ stretch main
#deb-src [arch=armhf] http://repos.rcn-ee.com/debian/ stretch main
deb http://debian.mirror.ac.za/debian stretch main 
#deb-src http://debian.mirror.ac.za/debian stretch main