Jo Achim wrote:
Subject: Urgent API Booking Issue: Persistent “Client email value is wrong” Error despite extensive testing
Dear Support Team,
I have been working to integrate the SimplyBook.me JSON-RPC API and have successfully isolated the issue to a persistent validation error in the client data fields.
Current Configuration Status:
Client Login Feature: Deactivated. The public API key is successfully fetching a client token.
Booking Parameters: The code currently sends the client’s name, email, and phone number as standard fields (not via the custom block), as all other combinations failed.
Error Received: Despite using the standard fields, the API consistently returns the error: Booking Error: Client email value is wrong (German original: Buchungsfehler: Client email value is wrong).
Last Failed Request Structure:
This is the exact JSON structure sent in the last request that failed with the email error:
JSON
{
“jsonrpc”: “2.0”,
“method”: “book”,
“params”: {
“serviceId”: 2,
“staffId”: 2,
“startTime”: “2026-06-01 11:30:00”,
“name”: “Max Mustermann”,
“email”: “max.mustermann.test@web.de”,
“phone”: “+49123456789”,
“custom”: {}
},
“id”: 5
}
Urgent Request for Account-Specific Validation Rules:
Since we have exhausted all logical parameter combinations, the issue must be related to an internal, account-specific validation rule.
Could you please check my account’s internal API validation settings and clarify the following:
Exact Field Names/Structure: Which precise field name structure does the book method expect for Client Name, Email, and Phone Number in my specific account configuration (e.g., name and email as standard fields, or are they mandatory Custom Fields with specific IDs)?
Email Validation: If the email must be sent via a standard field, why is the email field being rejected? (Is it a specific format requirement, or is the system internally expecting the email value to be sent via a Custom Field ID, even if Custom Fields are technically optional?)
Please provide the exact required JSON structure for the params object expected for a guest booking in our system.
Thank you very much for your support.
