Sphinx error after server update

I just discovered that the search functionality on my web site doesn’t work. Going through some logs, I find this:

unicorn.stdout.log: (…) Error connecting to Sphinx via the MySQL protocol. Error connecting to Sphinx via the MySQL protocol. Can’t connect to MySQL server on ‘127.0.0.1’ (…)

production.searchd.log: (…) [Sat Mar 24 01:56:16.713 2018] [27459] rotating indices (seamless=1) [Sat Mar 24 01:56:16.730 2018] [27459] rotating index ‘listing_delta’: started [Sat Mar 24 01:56:16.738 2018] [27459] rotating index ‘listing_delta’: success [Sat Mar 24 01:56:16.738 2018] [27459] rotating index: all indexes done [Tue Mar 27 10:28:26.365 2018] [27459] caught SIGTERM, shutting down [Tue Mar 27 10:28:26.926 2018] [27459] shutdown complete <and then nothing after March 27th>

I’m trying rake ts:restart, reindex, stop, start etc, but then I get error messages like this: rake aborted! ActiveRecord::AdapterNotSpecified: ‘development’ database is not configured. Available: [“production”] /path/to/file/environment.rb:17:in `<top (required)>’ Tasks: TOP => ts:index => environment

Everything worked fine before, but all of a sudden this search eror started to occur, and since the last line in the searhd log file is dated March 27, I suspect the behaviour is related to the upgrade.

Any hints on steps to resolve it?

Website: https://hengerdeling.no