In some cases, TYPO3 will give errors like "SQL error: Field xyz doesn't have a default value", when saving data in backend. This can be solved by disabling the MySQL-strict-mode "STRICT_TRANS_TABLES".
This strict mode can also be disabled through editing the file LocalConfiguration.php
'DB' => [
'Connections' => [
'Default' => [
'charset' => 'utf8',
//here goes DB settings
'initCommands' => 'SET sql_mode=\'\';',