Are they config time issues or runtime? That is to say, do the issues occur when you are integrating a new customer, or are they with current customers where something changes or pops up and there's an issue?
The most common problem is they forget to upgrade their yearly certificates or mess up the deployment. Other times they don’t have their servers correctly configured to read our manifest and thus miss certificate updates from our side. Or they mess up the payload configuration so we don’t receive the principal.
