Sending me an email to tell me "There is an error with [customer]'s website"[1] is about as useful to me as an email subject line consisting solely of "RE: website"[2].

I don't expect an essay long explanation with every contingency covered, but maybe we could start with any information at all?

[1] Note that, historically, approximately 33% of things you consider to be "errors" are either the way things are supposed to be (but you didn't understand what you were selling) or are exactly what you asked for.

[2] Note that every. single. thing. that I do here involves a website in one way or another. Thanks ever so much for narrowing it down.