Before you upgrade to Ghost v5.71.0 (Selfhosted only)

[thimiraonline]

Actually in August I migrated my server. At that point I installed v18.

Anyway, here is the guide by @Hannah

Replace 10 with 18

@Hannah

The DigitalOcean one-click App uses nodesource.

I recommend updating to Node v10 (v8 is almost end of life)

curl -sL https://deb.nodesource.com/setup_10.x | sudo -E bash -
sudo apt-get install -y nodejs
ghost update --force

One you’ve updated node, you must run ghost update --force in the ghost directory, this will force Ghost to update its dependencies to match Node v10, otherwise you’ll get more errors.