Hi Fabio,
Thanks for using Syncfusion Products.
As per our current implementation we don't have support for "the customization of exception raised while wrong data is entered in add/edit grid cell". We have logged this as a feature request in our database. We will implement this feature in any of our upcoming releases. We usually have an interval of at least three months between releases. The feature implementation would also greatly depend on the factors such as product design, code compatibility and complexity. We will update you when this feature has been implemented.
Please let us know if you have any concerns.
Regards,
Bala Murugan A.S