There will have to be a post mortem on this. The convention is to be as transparent as possible as to what went wrong. This helps to let current customers know that you found the problem, and have put plans in place to make sure it doesn't happen again.

The purpose of the signalling here is two fold.

1) If convincing enough (with details), you can keep current customers from moving to a competitor.

2) It also lets new customers see how you actually handle a crisis. If they can manage the crisis well enough, then you can point to this instance to prove your technical knowhow to handle their needs.

If they don't tell anything, or aren't transparent, then they can expect a mass exodus of customers.