M-168
When the site or an app is broken
First look at the status page. If something is down at our end it is said there, with what is affected and what is being done, so you do not spend an evening proving your phone is fine.
If the status page is clear, the card that gets fixed fastest says four things: what you tapped, what you expected, what happened instead, and roughly when. The page address and a screenshot are worth more than any description of the screen.
For an app, add the phone model and the app version from the account screen. For anything built on our API, quote the request id from the error: it takes an engineer straight to your own request in the log.