Thank you very much for the answer and the help, but I have tried to do what you indicate and it does not work either. It is about odoo 14, I don't know if you have been able to try it, it may not work. Could you try it and tell me if it works for you please?

I keep getting the same error.

This is the code part 

models_target.execute_kw(            
	​db_target,
	​uid_target,
	​password_target,
	​'res.partner',
	​'create',
	​[{
		​............ other fields ............
	​	​'vat': client_old['vat'],​
	​}],
	​{'context': {'no_vat_validation': True},}        
)

Error:

The VAT number [........] for the partner [........] seems to be invalid. \nNote: the expected format is ESA12345674'

Greetings and I hope for some solution that can help me. Thank you.

Hi,

In order to by pass the validation, you have to pass no_vat_validation as True in the context.

See this function in the code:

@api.constrains('vat', 'country_id')
def check_vat(self):
    # The context key 'no_vat_validation' allows you to store/set a VAT number without doing validations.
    # This is for API pushes from external platforms where you have no control over VAT numbers.
    if self.env.context.get('no_vat_validation'):
        return

Thanks