Inappropriate tone: Imagine a doctor performing a procedure and then suddenly saying “Oops! Something went wrong…” That is the last thing anyone wants to hear when the stakes are high, whether it’s surgery or someone’s source of income.

Technical jargon: Even in today’s world of user-centered design, technical jargon still sneaks its way into error messages.

Passing the blame: Try to focus on the problem, rather than the action that led to the problem.

Generic for no reason: Sometimes we don’t know what caused the error… but sometimes we do.

https://wix-ux.com/when-life-gives-you-lemons-write-better-error-messages-46c5223e1a2f