grep -r username /usr/local/cpanel/logs/access_log | grep login

dovecot: auth: Error: policy(?,xx.xx.xx.xx): Policy server HTTP error: Connection lost: read(127.0.0.1:579) failed: EOF (Request queued 2.784 secs ago, 1 attempts in 2.784 secs, 2.784 in other ioloops, connected 21.780 secs ago)

This error is caused by cPhulkd of cPanel, so you can temporally disable it, while investigating.

Than check for errors:
/usr/local/cpanel/logs/cphulkd_errors.log
/usr/local/cpanel/logs/cphulkd.log

Checking C compiler….Could not locate an executable “gcc” binary….Done ** Unrecoverable Error ** The C compiler is not functional and auto repair failed. Perl module installs require a working C compiler

You should find Compiler Access in WHM and enable it for some users.

If you are getting this error on Centos 7 OS

systemctl set-default multi-user.target
Removed symlink /etc/systemd/system/default.target.
Created symlink from /etc/systemd/system/default.target to /usr/lib/systemd/system/multi-user.target

/scripts/update_db_cache
/usr/local/cpanel/bin/setupdbmap

info [update_db_cache] MySQL is not enabled. Exiting now.
It means you need enable MySQL in Service Manager.

DeliveryReporter API internal failure: Cpanel::Exception::Database::Error/(XID 8vnjr9) The system received an error from the “SQLite” database “/var/cpanel/eximstats_db.sqlite3”: SQLITE_CORRUPT (database disk image is malformed) at /usr/local/cpanel/Cpanel/Exception/CORE.pm line 336, line 2. Cpanel::Exception::create(“Database::Error”, ARRAY(0xed7360)) called at /usr/local/cpanel/Cpanel/Exception.pm line 61 Cpanel::Exception::__ANON__(_CPANEL_HIDDEN_, ARRAY(0xed7360)) called at /usr/local/cpanel/Cpanel/DBI.pm line 200 Cpanel::DBI::_create_exception(Cpanel::DBI::SQLite::db=HASH(0xe9cf78) ….

cd /var/cpanel
mv eximstats_db.sqlite3 eximstats_db.sqlite3_old
/scripts/restartsrv_tailwatchd
/scripts/slurp_exim_mainlog –force


You should use user, not root whem running cpapi2:
cpapi2 --user=account_name Email delpop domain=domain.com email=user

/scripts/install_lets_encrypt_autossl_provider

If you have many SIGTERM and other services like exim, ftp also reboots without any logical reason, you can try disable cPanel or just cPanel TaskQueue Processing Daemon:

/usr/local/cpanel/etc/init/stopqueueprocd

then some magic:

mv /usr/local/cpanel/libexec/queueprocd /usr/local/cpanel/libexec/queueprocd___
mv /usr/local/cpanel/bin/servers_queue /usr/local/cpanel/bin/servers_queue___
mv /usr/local/cpanel/etc/init /usr/local/cpanel/etc/init___
mv /usr/local/cpanel/src/chkservd/chkserv.d/queueprocd /usr/local/cpanel/src/chkservd/chkserv.d/queueprocd___

then check:

cat /usr/local/apache/logs/error_log | grep shut

F=: Sender verify failed

cat /etc/userdomains | grep some-domain.com

some-domain.com: someuser

vi /usr/local/cpanel/3rdparty/etc/php.ini

Change

upload_max_filesize = 150M

AND

post_max_size = 150M

1) I ran a grep for the sessions that were currently in effect:

# grep “cpses_” /var/cpanel/databases/

2) I removed the following sections from any user’s yaml that matched the

cpses_########”:
dbs: {}
server: X.X.X.X

3) I removed each of the cpses_######## lines from /var/cpanel/databases/users.db

4) I ran the following command to update the user-data:

# /scripts/update_db_cache

5) I then removed all of the cpses_######## users from the mysql.user table to remove the users from mysql. This can be accomplished from the command line or from WHM>> PhpMyAdmin