ubuntu 에서 apt install 시 Failed to fetch 404 에러 발생

ubuntu 에서 가끔 apt install 시 주소를 찾지 못해 설치를 못하는 경우가 있다.

아래 처럼 나오는 경우

root@web:/etc# apt install snmp snmpd rrdtool
Reading package lists... Done
Building dependency tree
Reading state information... Done
The following packages were automatically installed and are no longer required:
  amd64-microcode intel-microcode iucode-tool libdbus-glib-1-2 libevdev2 libimobiledevice6 libplist3 libupower-glib3 libusbmuxd6
  linux-hwe-5.15-headers-5.15.0-41 thermald upower usbmuxd
Use 'apt autoremove' to remove them.
The following additional packages will be installed:
  fontconfig fontconfig-config fonts-dejavu-core libcairo2 libdatrie1 libdbi1 libfontconfig1 libgraphite2-3 libharfbuzz0b
  libmysqlclient21 libpango-1.0-0 libpangocairo-1.0-0 libpangoft2-1.0-0 libpixman-1-0 librrd8 libsensors-config libsensors5
  libsnmp-base libsnmp35 libthai-data libthai0 libxcb-render0 libxcb-shm0 libxrender1 mysql-common
Suggested packages:
  lm-sensors snmp-mibs-downloader librrds-perl snmptrapd
The following NEW packages will be installed:
  fontconfig fontconfig-config fonts-dejavu-core libcairo2 libdatrie1 libdbi1 libfontconfig1 libgraphite2-3 libharfbuzz0b
  libmysqlclient21 libpango-1.0-0 libpangocairo-1.0-0 libpangoft2-1.0-0 libpixman-1-0 librrd8 libsensors-config libsensors5
  libsnmp-base libsnmp35 libthai-data libthai0 libxcb-render0 libxcb-shm0 libxrender1 mysql-common rrdtool snmp snmpd
0 upgraded, 28 newly installed, 0 to remove and 155 not upgraded.
Need to get 1,304 kB/6,378 kB of archives.
After this operation, 23.6 MB of additional disk space will be used.
Do you want to continue? [Y/n] y
Ign:1 http://kr.archive.ubuntu.com/ubuntu focal-updates/main amd64 libmysqlclient21 amd64 8.0.39-0ubuntu0.20.04.1
Err:1 http://kr.archive.ubuntu.com/ubuntu focal-updates/main amd64 libmysqlclient21 amd64 8.0.39-0ubuntu0.20.04.1
  404  Not Found [IP: 185.125.190.83 80]
E: Failed to fetch http://kr.archive.ubuntu.com/ubuntu/pool/main/m/mysql-8.0/libmysqlclient21_8.0.39-0ubuntu0.20.04.1_amd64.deb 404  Not Found [IP: 185.125.190.83 80]
E: Unable to fetch some archives, maybe run apt-get update or try with --fix-missing?

여러가지 방법이 있는데 이중 하나는 apt 주소를 변경 해주면 된다.

위치 : cd /etc/apt

sources.list 파일은 백업을 한다.

백업 : cp snmpd.conf snmpd.conf-org