fatal error when updating a membership subscription date

I'm in All Members, and when I go to Subscription Details, I want to change the Expire Date but when I do it throws a fatal error:

Fatal error: Uncaught exception 'Exception' with message 'You cannot register a new account, because you are already logged in.' in /home/suzukiwa/public_html/wp-content/plugins/membership/app/model/class-ms-model-member.php:989 Stack trace: #0 /home/suzukiwa/public_html/wp-content/plugins/membership/app/model/class-ms-model-member.php(939): MS_Model_Member->create_new_user() #1 /home/suzukiwa/public_html/wp-content/plugins/membership/app/controller/class-ms-controller-member.php(368): MS_Model_Member->save() #2 [internal function]: MS_Controller_Member->members_admin_page_process_editor('') #3 /home/suzukiwa/public_html/wp-includes/plugin.php(503): call_user_func_array(Array, Array) #4 /home/suzukiwa/public_html/wp-admin/admin.php(226): do_action('load-membership...') #5 {main} thrown in /home/suzukiwa/public_html/wp-content/plugins/membership/app/model/class-ms-model-member.php on line 989

It says Edit Member at the top but the Add Member is highlighted in the admin menu. Not sure if it's trying to add a new member or?

Thanks