[Fri Sep 30 21:55:39.256864 2016] [fcgid:warn] [pid 55684] (110)Connection timed out: [client 125.20.49.52:62176] mod_fcgid: ap_pass_brigade failed in handle_request_ipc function, referer: https://sushovan.in/wp-admin/update-core.php

Got good help from https://www.virtualmin.com/node/7529

Fixed with this configuration change in fcgid.conf file in /etc/apache2/mods-available

FcgidConnectTimeout 60
IPCConnectTimeout 60
IPCCommTimeout 600