Tried to update ERPNext from V12 to V13. I can see the " Sorry! We will be back soon." screen. ERPNext update worked successfully but I can see below log in “web.error.log”
[2022-02-21 13:38:11 -0800] [1140] [INFO] Starting gunicorn 20.1.0
[2022-02-21 13:38:11 -0800] [1140] [ERROR] Retrying in 1 second.
[2022-02-21 13:38:12 -0800] [1140] [ERROR] Retrying in 1 second.
[2022-02-21 13:38:13 -0800] [1140] [ERROR] Retrying in 1 second.
[2022-02-21 13:38:14 -0800] [1140] [ERROR] Retrying in 1 second.
[2022-02-21 13:38:15 -0800] [1140] [ERROR] Retrying in 1 second.
[2022-02-21 13:38:16 -0800] [1140] [ERROR] Can't connect to ('127.0.0.1', 80)