To solve the error “SyntaxError: JSON.parse: unexpected character at line 1 column 1 of the JSON data” when trying to update a sale order status, try these solutions:

  1. Check HTTPS_SERVER property inadmin/config.php is correct.
  2. Check you have an API user and that user is associated with the main store

Navigate to the API user list

Navigate to OC API

Set the store API user

Settings API user