Last week I nuked my personal lemmy instance while trying to upgrade to 0.18.0. Due to some technical issues, I decided to keep the server offline while waiting for the new releases. During this process I deleted the database and all config files while trying to debug. Finally, after 1 week, I decided to try the latest release candidate and the instance is back up. I thought I would have to manually re-subscribe to all my communities as I saw an empty list of subscribed communities, but over the next few hours something amazing happened. One by one all my previously subscribed communities appeared on the Communities->All tab 😱 🤯. All I had to do was click subscribe. I guess this would not have happened if I had used a different username or domain name for my instance. TLDR: Fediverse/lemmy restored my subscribed communities after the instance was offline for 1 week and the database was reset.