While adding/updating list item, REST endpoint should be like given below:
Where ListName is Display name of the SharePoint List.
In your code, itemType is ListItemEntityTypeFullName property of List.
The ListItemEntityTypeFullName property is especially important if you want to create and ...
Here is the code for attaching an 'ItemAdded' event receiver with CSOM:
var serviceUrl = "https://remote-event-receiver-service-url";
var list = clientContext.Web.Lists.GetByTitle("TestList1");
var eventReceiverInfo = new EventReceiverDefinitionCreationInformation
EventType = EventReceiverType.ItemAdded,
Synchronization = ...
It is a known error if you created your App Catalog recently, you should wait for 20-40 minutes and redeploy your package, it should work. if did not check your codes for error
and see if there is any error on the console
hope this help someone who face same issue