Application_CallbackNotAllowed

 The following error message will be displayed if, on the table that you are trying to read from or write to, has end-user confirmation dialog boxes, message boxes or any other page constructs in the code. Because a web service runs independently of a user interface, running this type of code causes the code to throw an exception. The exception can be caught and handled, but the web service won't complete.If you see this error, you would need to disable any confirmation dialog boxes related to that table in Business Central because ODATA does not support it. 


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.