The error message you are seeing suggests that there may be an issue with the JSON data being returned by the controller. To resolve this, you may want to check that the data being returned by the controller is properly formatted as JSON.

In your code, you are using the request.render method to render the "thank you" page. However, this method does not return a JSON response, but rather a rendered template. To return a JSON response, you can use the json.dumps method to serialize a Python object into a JSON-formatted string, and then return that string using the werkzeug.wrappers.Response object.

Here's an example of how you could modify your controller to return a JSON response and redirect to the "thank you" page:

python

import json
from werkzeug.wrappers import Response

@http.route('/custom_module/create_record', methods=['POST'], type='http', auth='public', website=True)
def create_complaint(self, **kwargs):
# Create the record in your custom module
request.env['custom_module'].sudo().create({'employee_id': 1})
 
# Build the JSON response
response_data = {'success': True, 'redirect_url': '/contactus-thank-you'}
response_json = json.dumps(response_data)
 
# Return the JSON response
return Response(response_json, content_type='application/json')

In this example, the controller creates the record in your custom module, builds a JSON object containing a success flag and the URL of the "thank you" page, and then serializes the object into a JSON-formatted string using the json.dumps method. Finally, the controller returns a werkzeug.wrappers.Response object containing the JSON string and the content_type parameter set to application/json, indicating that the response is a JSON object.

Hello Cristian,

Unfortunately, this is my problem too.

In Odoo 13 it worked without any problem, but in Odoo 16 I have encountered exactly the same json problem. 

Did you find a solution for this error?

I used:

​ import json

​ from werkzeug.wrappers import Respo

 but it didn't work.

Best Regards