The conversation becomes safer when a small admission does not trigger a large judgment.

People tell you the truth in proportion to what it costs them. If admitting a small mistake reliably produces a lecture, a long silence or a conclusion about their character, they will simply stop admitting things, and you will find out about problems much later and from someone else. The size of your reaction sets the price of honesty.

When someone owns up to something minor, keep your response minor. Say thanks for telling me and deal with the practical part. Save the serious conversations for serious matters, and notice whether people around you have started volunteering information they used to hide.