I checked the status page and it looks like everything is up and running. However, the majority of my feature services are returning the following error:
The layer, LAYERNAME cannot be added to the map.
You can check the status and report an outage here....
ArcGIS Online Health Dashboard
It's not down for my organization, but we may be on a different hosted server.
Sometimes if I wait a long while, my 'down' feature services will come back up. But, checking the status site is a good place to start, like Leon mentioned.
Thanks, I wonder why this happens. Perhaps maintenance .... i just wish they'd give us a heads up.
With generic errors such as "The layer, <LayerName>, cannot be added to the map", sometimes you can get more error information using Fiddler. Fiddler captures the requests and responses and will often expose ArcGIS Online back-end errors that you would not be able to see otherwise.
If you feel up to a bit of reading, we have a blog discussing Fiddler at Monitoring web service requests using Fiddler . Or, if you'd like, go ahead and give us a call at Esri Support Services, and we can assist you in setting up Fiddler and looking at the requests and responses and do some troubleshooting. We can also investigate if there's something going on with your organization or content, or ArcGIS Online as a whole.
Esri Support Services
Retrieving data ...