After years of running one app that runs as a service and performs account maintenance functions for one user, the app has suddenly started to require daily maintenance. Originally, an access token and secret were created. This pair of values was added to the config file of the windows service, and the app has run without any issues for a at least 20 months. Suddenly, the app starts getting authentication errors and going to the Manage Your Apps and looking at the authentication tab shows a message like You have never authorized your own account and the create access token button is visible. Clicking the button, and creating a new access token and key, copying these values into the config file, and restarting the service work, but this is happening every day in the evening, and we perform work overnight which is not being performed now. Has there been a change, or why is this happening now, and most importantly, what can I do to fix this situation?? Remember, this app runs as a windows service on a server and there is no ‘web browser’ interface to this app.