In ArcGIS Online, attempts to access a feature service using Map Viewer fail, and the following error message is returned:
Error: Unknown resource - could not find token service endpoint
Additionally, attempts to access the same feature service using Map Viewer Classic fail, with the error message below returned.
Error: The layer cannot be added to the map.
The cached version of the website stored on the local machine does not match the cached version loaded from the browser.
On the local machine, clear the browser cache to resolve the issue. Depending on the browser used, refer to the links provided for instructions.