While validating AI model on target it gives me error as STM32com exception: Invalid payload: ack instead node.

[ANaik.16]

I am trying to validate Keras model using STM32 cubeMX on STM32f407 discovery kit. 

I am able to generate code and flash into board. But, after that when I tried to validate on target it gives me error as STM32com exception: Invalid payload: ack instead node. 

I search on internet about these but nothing is given. Also, in User manual, Nothing is given about these error.

I have attached screenshot of error.

Can anyone please help me to get out of this?