by Peter Meint Heida.
When I use the next call:
http://website.com/webservice/rest/server.php?wstoken=#######&moodlewsrestformat=json&wsfunction=core_user_create_users&users[0][username]=9999999999&users[0][firstname]=Test&users[0][lastname]=123456&users[0][email]=test@test.nl&users[0][createpassword]=1&users[0][customfields][0][type]=winkel&users[0][customfields][0][value]=Filiaalmedewerker
The customfield is created, but the value is not set. Which means in the database the record in the table prf_user_info_data is created, but the 'data' field of the record is not filled/set.
What is going wrong?