TYPO3 Core

When configuring an additional or new database like this:

$connectionParams = [
    'dbname' => '..',
    'user' => '..',
    'password' => '..',
    'host' => '..',
    'driver' => '..'
];
$GLOBALS['TYPO3_CONF_VARS']['DB']['Connections']['..'] =  $connectionParams;

the option 'charset' can be left out without issue of connection.

ConnectionPool will default to a new charset setting, but not a valid one at this line:
https://api.typo3.org/typo3cms/8/html/_connection_pool_8php_source.html#l00146
The charset 'utf-8' is invalid and content loaded from a UTF-8 database like this, will have unknown characters in them, causing issues when the conent is parsed via htmlspecialchars() for example.

As solution, the charset configuration should be required or default to the proper string 'utf8'.