When to use please in ux writing?
Microsoft releases their UX guidelines and in it they explicitly say, Avoid the word “please,” except in situations in which the user is asked to do something inconvenient (such as waiting) or the software is to blame for the situation.
Should you say please in error messages?
Use “please” only rarely, if ever. Sometimes lengthy instructions or error messages might need a touch of politeness added to one of several sentences, but generally, do not use “please” in English. If you still feel the need, at least avoid using “please” more than once in one text or group of sentences.