cPanel 500 error "Out of memory!"

При попытке просмотра списка поддоменов в cPanel появилась ошибка 500.
Если во время воспроизведения ошибки посмотреть в лог, то можно увидеть, что не хватает памяти панели:
# tail -f /usr/local/cpanel/logs/error_log
Out of memory!
Cpanel::FHTrap was not closed properly and was unable to return the result: []
[2016-03-21 19:01:37 +0300] warn [cpsrvd] The subprocess (cpanel (cpanel)) exited with an error: The subprocess reported error number 1 when it ended. at /usr/local/cpanel/Cpanel/Server/Handlers/SubProcess.pm line 155.
Cpanel::Server::Handlers::SubProcess::_report_subprocess_errors(Cpanel::Server::Handlers::SubProcess=HASH(0x26064d0)) called at /usr/local/cpanel/Cpanel/Server/Handlers/SubProcess.pm line 72
Cpanel::Server::Handlers::SubProcess::handler(Cpanel::Server::Handlers::SubProcess=HASH(0x26064d0), "subprocess_name", "cpanel (cpanel)", "subprocess_read_handle", IO::Handle=GLOB(0x2605eb8), "subprocess_write_handle", IO::Handle=GLOB(0x26062c0), "api_type", "html", ...) called at cpsrvd.pl line 6421
cpanel::cpsrvd::cpHandler("app", "cpanel", "document", "./frontend/x3/subdomain/index.html") called at cpsrvd.pl line 2387
cpanel::cpsrvd::dodoc_cpaneld() called at cpsrvd.pl line 1645
cpanel::cpsrvd::dodoc(HASH(0x1802ea0)) called at cpsrvd.pl line 1328
cpanel::cpsrvd::handle_one_connection() called at cpsrvd.pl line 844
cpanel::cpsrvd::script() called at cpsrvd.pl line 339

Смотрим сколько памяти у нас выделено под панель:
# grep maxmem /var/cpanel/cpanel.config
maxmem=2048

Немного добавим памяти:
# vim /var/cpanel/cpanel.config
maxmem=2548
# service cpanel restart

Ошибка исчезает.