It looks like a database configuration mismatch. Given "Connection refused", I'm betting it doesn't load ip/port/credentials correctly from the configuration.

I haven't been looking at L5 since it was released, but when I last played with it, they moved database configuration to .env files. so it would be a good place to start. If you haven't already, check out the 4.2 to 5.0 upgrade doc for hints to this.

I had copied/edited the .env file, and placed all the same credentials as my L4 app which still works ok, so I'm still pretty stuck on this... :-(

[update] Just tried this on another new installed L5, running with MAMP, and if I have "localhost" in the .env file I get a No such file or directory message, whereas if i have 127.0.0.1 instead I get Connection refused.