I'm sorry for that. That's clearly not the experience we want our users to have. Unfortunately there are many moving parts and points of failure.
We try to communicate know errors to the users wherever possible but there are also a series unexpected errors, which we only can react to with a generic error message. I can see that the "whoops" is particularly frustrating in such a situation...
However, if we knew what the problem was and how to fix it we would do this behind the scene rather than showing an error message.
Such errors, are relatively rare given the thousands of documents formatted every day, but if it happens it's problematic. How do we address that?
Our support team has a median response time of 4-6 hours and we try to fix things for our customers if things break. We have technical logs on our side which helps with that. If that did not work in your case we clearly must get better with that.
Of course we also try to address the underlying issues if we can come up with a fix to avoid errors in the future.