You cannot register user using a “used” emails. Used emails included your Wix account as well. For contacts, it is different from Site Members, please see the wix CRM backend API to create contact (not site member that can login). Create contact can be using duplicated emails.
Can you open the “Members/PrivateMembersData” database in your editor to check if it is already exist? – Checked and does not exist
If this issue still occurs, please post your FULL code here Here is my FULL server side code :
export function processEmailRegistration(email, password) {
return new Promise((resolve, reject) => {
wixUsersBackend.register(email, password)
.then((results) => {
resolve(results);
})
.catch((error) => {
console.log("Registration error ", error);
reject(error)
})