Restrict SAVE functionality and throw Error Message on BP change

HI all,

I am performing certain validations when the Marketing Attribute of a BP is changed. For certain conditions, I will have to stop the changes from getting saved and throw up an error message. Please suggest how to stop SAVE functionality and throw Error Message in both GUI and PCUI.

I tried to raise the exception DO_NOT_SAVE. But, it does not exist. I am developing the code in the Badi BUPA_GENERAL_UPDATE.

Thanks,

Preetha