How much space have you got? (df -h)
How many backups are you retaining on your droplet? (move them to S3 if you haven’t already done so)
Is your content from an import or a restore? (You may be carrying excess baggage from that. See here.
I’m guessing that your instance is a bit behind, the rebuild updated ./launcher itself (You got the “new” You have less than launcher message), then failed because docker is out of date (iirc @Falco stated that the new cleanup will work even if the disk is at 100%).