Has Prime 365 (or any SharePoint App) suddenly stoped working in your Microsoft Office 365 environment, with the following exception:
System.IdentityModel.Tokens.SecurityTokenException: Invalid JWT token. Could not resolve issuer token.
This is because the Shared Secret of your apps expire one year after the creation, and you have to renew it manually. This article on MSDN explains how to renew a Shared Secret for an app, without changing the Client ID: “How to Replace an expiring client secret in an app for SharePoint”.
Better yet, please follow this article that we have created with detailed instruction on Updating an expiring Client Secret. It even walks you thought the steps to generate a new Client Secret that is valid for 3 years.