I am uploading a geojson to "My Content". I was attempting to create a hosted feature layer out of this geojson file. However, when I filled in all the fields and clicked confirm, there was a pop up saying "An error occurred" (without further indication what it is). The content (geojson) and feature layer was actually created, but when I tried to click the "view" button of the featured layer url, it gave me a page of the "ArcGIS REST Services Directory" which said: "invalid URL". When trying to use this url to create a geojson layer in my application (using the js api), it gave an error saying: "Unexpected token < in JSON at position 0".
I then went on trying to see if the uploaded file was corrupted, but after I downloaded the geojson file from "My Content", the file I got seems to be a valid geojson.