After updating from 1.5 to 1.6 via Composer, I have started seeing those errors every time I'm installing any module using the admin back-end. When using drush the same thing happens.
Please see the exact error message:
Drupal\Core\Config\UnsupportedDataTypeConfigException: Invalid data type in config auto_username.settings, found in file modules/contrib/auto_username/config/install/auto_username.settings.yml: The string "!php/const Drupal\auto_username\AutoUsernamePunctuationOptions::CASE_LEAVE_AS_IS" could not be parsed as a constant. Did you forget to pass the "Yaml::PARSE_CONSTANT" flag to the parser? at line 5 (near "aun_case: !php/const Drupal\auto_username\AutoUsernamePunctuationOptions::CASE_LEAVE_AS_IS") in Drupal\Core\Config\FileStorage->read() (line 118 of /var/www/devel.centrummedyczne-zuza.pl/web/core/lib/Drupal/Core/Config/FileStorage.php).
I have also tried to update to the devel version but no joy.
Active
1.6
Code
My bad is a dupe of Do not use constant AUN_CASE_LEAVE_ASIS in auto_username.settings.yml 🐛 Do not use constant AUN_CASE_LEAVE_ASIS in auto_username.settings.yml RTBC