Should we use please for validation messages for e-commerce applications

1. Should you use please in error messages?
2. What is a validation message?
3. What causes validation error?

Should you use please in error messages?

Don't. Avoid using “please” and “sorry”. Saying "sorry" in error messages can make the situation worse by causing errors to appear more severe than they actually are. Similarly, saying "please" can undermine the authority and credibility of your message and lead people to think a required step is optional.

What is a validation message?

When you have validation enabled, you can receive messages that validate a filter or function expression. You can receive either warnings or errors based on the information that you have specified in your mapping specification.

What causes validation error?

Validation errors typically occur when a request is malformed -- usually because a field has not been given the correct value type, or the JSON is misformatted.