CRED User Fields Control is failing due to a Undefined property

Symptoms

Visiting the page

admin.php?page=CRED_User_Fields

a PHP error can be seen on top of the screen (If WP Debug is enabled):

( ! ) Notice: Undefined property: 
CRED_Fields_Model::$_custom_user_fields_option in 
.../cred/library/toolset/cred/embedded/models/Fields.php on line 263

This error makes it impossible to edit registered custom fields.

Workaround

This issue will be fixed in the next release of Toolset CRED.

In the meantime, you can download this file, extract it and replace the

Fields.php and FieldsAbstract.php file in /plugins/cred-frontend-editor/library/toolset/cred/embedded/models/ folder.

Please remember to keep a backup of your site and database before doing this.