That message can't be changed, but you can suppress it. You can edit the page template used by your page, go to the Notification sub-template region and replace #MESSAGE# with an application item substitution like &MY_VALIDATION_ERR. . Then create that application item named MY_VALIDATION_ERR. Then a validation (function returning boolean) can do something like:
if <validation check fails> then
:MY_VALIDATION_ERR := 'some bad errors happened';
:MY_VALIDATION_ERR := null;
That's the general idea anyway, you might not want to go to that much trouble.
Thanks for your reply....
What will be the condition of the following if :
if <validation check fails> ??
I have a lot of pages, each page with many validations,
many validations types (items not null, pl/sql....).
As I said, that technique would work for PL/SQL function validations in which you must code the validation pass/fail logic. I don't know of a way to do what you asked without your having to re-implement all your validations in this way , which is why I said it might be too much trouble.