Updating software

• Backup the SD card image for larger upgrade → see High Endurance Micro-SDHC card 32 GB 100 MB/s UHS Class 3 by SANDISK
• Update Repetier Server (using software frontend)
• Update Grafana → use /opt/upgrade-grafana.sh script

apt update
apt upgrade

#fix some broken keys if required:
curl -sS https://dl.yarnpkg.com/debian/pubkey.gpg | sudo apt-key add -

#An error occurred during the signature verification. The repository is not updated and the previous index files will be used. GPG error: http://deb.debian.org/debian unstable InRelease: The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 648ACFD622F3D138 NO_PUBKEY 0E98404D386FA1D9
sudo apt-key adv --keyserver keyserver.ubuntu.com --recv-keys 648ACFD622F3D138