Client: This web app you created doesn’t work! We get an error message and then a blank screen. I’ve attached a screenshot, please use it to figure out what’s wrong.
I open the screenshot. Fair enough: it’s of a blank screen.
Me: Can you take a screenshot of the error message?
Client: What’ll that tell you?
Me: What’s wrong.
Client: What’s the first screenshot tell you?
Me: Your screen’s resolution.