We asked users to rate our error messages. The worst-rated one had the highest comprehension.

We ran a study with 600 users. We showed them our top 10 error messages and asked two things: did you understand what happened, and how did this message make you feel?

The message that scored highest on comprehension — 91% understood exactly what went wrong — scored lowest on sentiment. Users described it as "cold," "blunt," and "accusatory."

The message: "Your file exceeded the 25 MB limit. It was not uploaded."

It was accurate, specific, and complete. And it made people feel bad. The friendly messages that scored well on sentiment scored worse on comprehension — users liked them but were not sure what had happened.

We rewrote the cold-but-clear message to keep every fact and change the frame: "This file is 31 MB. The limit is 25 MB. Here is how to reduce it." Comprehension stayed at 91%. Sentiment rose to match our friendliest message.

Clarity and warmth are not opposites. We had been choosing one at a time. Have you tested your error messages for both?