What could be causing a 503 error?
Can you elaborate a little more on where you are getting this error? You posted this in ArcGIS Online. I found a support article con a 503 error: Error: HTTP Status 503 - Web services handler not initialized , but this is related to ArcGIS Server and probably not relevant for your situation.
This was happening under developers.arcgis.com. I later signed out and signed in again and the error disappeared. When I view the layer through ArcGIS online, the map would indicate that it cannot load the layer. I went incognito and the problem disappeared.
It sounds like it's solved. But, moving forward, screenshots are helpful too.
An example is the snapshot above, when I try to open the Geoform on normal chrome browser. On trying to load the respective webmap, I get the error below:
The same opens properly when am in incognito
Just to verify, in a normal session you log in with an AGOL account (what type of account is this)? When you go incognito do you sign in or are you accessing the layer anonymously?
Account is developer account. I access the layer using the same account, not anonymously
I have multiple errors on web maps and Hosted feature services today, Same 503 errors, features not loading in webapps, ArcGIS Pro time outs etc.
All hosted on the 7 hive. https://services7.arcgis.com/Q1bahANZxFra3G0H/ArcGIS/rest/services
Getting multiple hosted feature load errors on web map refreshes.