We have a custom activity that worked properly this Friday (2017-04-06). Today there's an error code in browser console that config.js is not found and gets a 404. When creating a new journey the custom activity doesn't launch and the error message
"One or more custom activities failed to load. Verify that custom activity endpoints are valid and refresh the Interaction."
appears. The endpoint URL has not changed since it worked. We also tried renaming the file where we host the app to config.js but still no luck.
I cannot get any information what config.js is supposed to contain, all documentation is about config.json. Does anyone have any suggestions on what to do?