The REST service returned a status code that is not 20x - i.e. not OK - Status code received: 400 Bad Request Response body: {"error":{"code":"Application_CallbackNotAllowed","message":"Microsoft Dynamics 365 Business Central Data Services attempted to issue a client callback to show a confirmation dialog box: Your change might update related records, which can take a while. Do you want to continue? (Page 21 Customer Card). Client callbacks are not supported on Microsoft Dynamics 365 Business Central Data Services. CorrelationId: fee0f3d7-492c-4273-b08e-a7eee60bd75e."}}
In order to disable them, you would need to go to My Notifications ( you can find it via My Settings) page and disable the dialog box. Once you've done that, you should not see this error anymore.