Fatal error: Uncaught TypeError: Argument 1 passed to WP_Translation_Controller::set_locale() must be of the type string, null given, called in /usr/home/mig/domains/senju.at/public_html/wp-includes/l10n.php on line 803 and defined in /usr/home/mig/domains/senju.at/public_html/wp-includes/l10n/class-wp-translation-controller.php:87
Stack trace:
#0 /usr/home/mig/domains/senju.at/public_html/wp-includes/l10n.php(803): WP_Translation_Controller->set_locale(NULL)
#1 /usr/home/mig/domains/senju.at/public_html/wp-includes/l10n.php(959): load_textdomain('default', '/usr/home/mig/d...', NULL)
#2 /usr/home/mig/domains/senju.at/public_html/wp-settings.php(641): load_default_textdomain()
#3 /usr/home/mig/domains/senju.at/public_html/wp-config.php(80): require_once('/usr/home/mig/d...')
#4 /usr/home/mig/domains/senju.at/public_html/wp-load.php(50): require_once('/usr/home/mig/d...')
#5 /usr/home/mig/domains/senju.at/public_html/wp-blog-header.php(13): require_once('/usr/home/mig/d...')
#6 /usr/home/mig/domains/senju.at/public_html/in in /usr/home/mig/domains/senju.at/public_html/wp-includes/l10n/class-wp-translation-controller.php on line 87

Fatal error: Uncaught TypeError: Argument 1 passed to WP_Translation_Controller::set_locale() must be of the type string, null given, called in /usr/home/mig/domains/senju.at/public_html/wp-includes/l10n.php on line 803 and defined in /usr/home/mig/domains/senju.at/public_html/wp-includes/l10n/class-wp-translation-controller.php:87
Stack trace:
#0 /usr/home/mig/domains/senju.at/public_html/wp-includes/l10n.php(803): WP_Translation_Controller->set_locale(NULL)
#1 /usr/home/mig/domains/senju.at/public_html/wp-includes/l10n.php(959): load_textdomain('default', '/usr/home/mig/d...', NULL)
#2 /usr/home/mig/domains/senju.at/public_html/wp-includes/class-wp-fatal-error-handler.php(49): load_default_textdomain()
#3 [internal function]: WP_Fatal_Error_Handler->handle()
#4 {main}
  thrown in /usr/home/mig/domains/senju.at/public_html/wp-includes/l10n/class-wp-translation-controller.php on line 87