If the directory above the document root is not writable, the logs_blesta directory cannot be created, and the migrator fails with an error:

Instead, it should fail silently and just not create or set the logs directory. I assume that with no log directory set in the settings, Monolog will just not attempt to write the file at all. If it does try to write it, it may write to a bad location or produce an error, need to make sure it does not.

[2017-07-18 19:58:11] general.ERROR: exception 'UnknownException' with message 'mkdir(): Permission denied' in /var/www/html/blesta/components/upgrades/tasks/upgrade4_1_0_b1.php:248 Stack trace: #0 [internal function]: UnknownException::setErrorHandler(2, 'mkdir(): Permis...', '/var/www/html/b...', 248, Array) #1 /var/www/html/blesta/vendors/monolog/monolog/src/Monolog/ErrorHandler.php(164): call_user_func(Array, 2, 'mkdir(): Permis...', '/var/www/html/b...', 248, Array) #2 [internal function]: Monolog\ErrorHandler->handleError(2, 'mkdir(): Permis...', '/var/www/html/b...', 248, Array) #3 /var/www/html/blesta/components/upgrades/tasks/upgrade4_1_0_b1.php(248): mkdir('/var/www/html/l...', 493) #4 /var/www/html/blesta/components/upgrades/tasks/upgrade4_1_0_b1.php(63): Upgrade4_1_0B1->createLogDirectory() #5 /var/www/html/blesta/components/upgrades/upgrades.php(266): Upgrade4_1_0B1->process('createLogDirect...') #6 /var/www/html/blesta/components/upgrades/upgrades.php(101): Upgrades->processObject(Object(Upgrade4_1_0B1), NULL) #7 /var/www/html/blesta/app/controllers/admin_upgrade.php(108): Upgrades->start('4.0.0-b6', '4.1.0-b1') #8 /var/www/html/blesta/vendors/minphp/bridge/src/Lib/Dispatcher.php(143): AdminUpgrade->process() #9 /var/www/html/blesta/index.php(21): Dispatcher::dispatch('/admin/upgrade/...') #10