Remote event receiver not firing (SharePoint Online)

Question

I have downloaded the PnP sample project ECM.AutoTagging and have configured an azure service bus for debugging, have created new client id/token and updated the app manifest/web.config and so on. I can set breakpoints on library creation and the code to attach the event receiver is run. I check with PnP PowerShell that is has been added also:

$list = Get-PnPList -Identity AutoTaggingSampleItemAdded
Get-PnPEventReceiver -List $list

ReceiverName                                             ReceiverId                           SequenceNumber EventType
------------                                             ----------                           -------------- ---------
PnPAutoTaggingItemAdded                                  b599481b-76e8-4159-8a82-a59b5b8f0f18 0              ItemAdded

but it's not firing when I'm creating a new document or uploading one to the library.

The code

        public SPRemoteEventResult ProcessEvent(SPRemoteEventProperties properties)
        {
            SPRemoteEventResult _result = new SPRemoteEventResult();

            try 
            { 
                switch(properties.EventType)
                {
                    case SPRemoteEventType.ItemAdded:
                        HandleAutoTaggingItemAdded(properties);
                        break;
                    case SPRemoteEventType.ItemAdding:
                        HandleAutoTaggingItemAdding(properties, _result);
                        break;
                }
                _result.Status = SPRemoteEventServiceStatus.Continue;
            }
            catch(Exception)
            {
                //You should log here.               
            }
            return _result;
        }

Isn't being hit. I haven't changed any code from the example so I'm not sure what I could be missing? The code example is three years old so could how to do things have been updated since then?

Thanks in advance.

Answer 1

Hard to say if this is all you need but ItemAdded events use the ProcessOneWayEvent method and not ProcessEvent. Notice how ProcessEvent returns a value; that's for async receivers like ItemAdding. That code will never get hit on ItemAdded.

https://docs.microsoft.com/en-us/sharepoint/dev/sp-add-ins/create-a-remote-event-receiver-in-sharepoint-add-ins

Also your web server's HTTP logs should be able to tell conclusively if requests have been made to it.

Answer 2

If you are using the modern library UI, I noticed events are not being triggered at all.

Try it on classic UI, if it works- you know this is the cause.

I have no solution currently for modern library UI supporting events, modern UI seems to broke event receivers.