Fatal error: Uncaught Error: Interface "Psr\Http\Client\ClientExceptionInterface" not found in /var/www/html1/wp-content/plugins/zettle-pos-integration/vendor/psr/http-client/src/RequestExceptionInterface.php:14 Stack trace: #0 {main} thrown in /var/www/html1/wp-content/plugins/zettle-pos-integration/vendor/psr/http-client/src/RequestExceptionInterface.php on line 14