Zuora authentication is now using Plugin API

In order to add support for oAuth2, Drupal\zuora\Annotation\Authentication plugin was introduced. However, since this module didn't provide an interface for saving credentials via UI there is no upgrade path provided for the new data structure.

You were most likely using following snippet in your settings.php file

$config['zuora.settings']['access_key_id'] = 'yourusername';
$config['zuora.settings']['access_secret_key'] = 'yourpassword';

which now should become

$config['zuora.settings']['plugin'] = 'username_password';
$config['zuora.settings']['configuration']['access_key_id'] = 'yourusername';
$config['zuora.settings']['configuration']['access_secret_key'] = 'yourpassword';

You can migrate to oAuth2 by obtaining oAuth credentials for your account from Zuora and configuring the module:

$config['zuora.settings']['plugin'] = 'oauth2';
$config['zuora.settings']['configuration']['client_id'] = 'yourclientid';
$config['zuora.settings']['configuration']['client_secret'] = 'yourclientsecret';