# Major Version Upgrade on Debian

- make a snapshot/backup of the machine
- check the running clusters using `pg_lsclusters` command
- drop the new cluster (the one running the target version) `sudo -u postgres pg_dropcluster --stop 15 main`
- (optional) if you are ssh-ing from a macOS/Item2 the LC\_CTYPE is wrongly set 
    - run `export LC_CTYPE=en_US.UTF-8 export LC_ALL=en_US.UTF-8`
- upgrade the old cluster `sudo -u postgres pg_upgradecluster 13 main`
- check the running clusters using `pg_lsclusters` command
- drop the old cluster (be sure the upgrade was successful) `sudo -u postgres pg_dropcluster 13 main`
- uninstall old postgresql packages