I have a single page application that interacts with SharePoint strictly through the use of its web services. Some parts are using CSOM and others are using REST. On page load it calls contextinfo to get the __REQUESTDIGEST value. Recently that call stopped working and now gives a vague error message. All users of the site have an AD account and should be authenticated using windows authentication.
The only change that happened recently is that the web application changed from using Classic authentication to using Claims based. I am not sure if this issue started right after that but it could be related.
Https://[hostHeaderSiteURL]/_api/contextinfo
Request Error
The server encountered an error processing the request. See server logs for more details.
Server Log:
02/01/2017 10:14:17.87 w3wp.exe (0x2550) 0x6884 SharePoint Foundation Monitoring nasqMedium Entering monitored scope (Request (GET:https://[url]/_api/contextinfo)). Parent No02/01/2017 10:14:17.87 w3wp.exe (0x2550) 0x6884 SharePoint Foundation Logging Correlation Data xmnvMedium Name=Request (GET:https://[url]/_api/contextinfo)84cdd09d-70d9-105e-dc2c-114f79b16d8c
02/01/2017 10:14:17.87 w3wp.exe (0x2550) 0x6884 SharePoint Foundation Micro Trace uls4Medium Micro Trace Tags: 0 nasq84cdd09d-70d9-105e-dc2c-114f79b16d8c
02/01/2017 10:14:17.87 w3wp.exe (0x2550) 0x6884 SharePoint Foundation Monitoring b4lyMedium Leaving Monitored Scope (Request (GET:https://[url]/_api/contextinfo)). Execution Time=6.1988325331850884cdd09d-70d9-105e-dc2c-114f79b16d8c