Scheduler with Resources not showing any events

[SrcDev]

Hi, 

after updating to Kendo version v2021.3.1109. when we bind data to a ASP.NET MVC Scheduler that has Resources defined, no events are shown.  This is happening after an update from Kendo version: 2017.3..913. In this version everything was working correctly. The error we get in Chrome developer console is:

kendo.all.js:114061 Uncaught TypeError: r[d].get is not a function
    at r.eventResources (kendo.all.js:114061)
    at r._createEventElement (kendo.all.js:116100)
    at r._renderEvents (kendo.all.js:116221)
    at render (kendo.all.js:116300)
    at init.refresh (kendo.all.js:127143)
    at init.e (jquery-3.1.1.min.js:2)
    at init.trigger (kendo.all.js:164)
    at init._process (kendo.all.js:8137)
    at init.success (kendo.all.js:7833)
    at success (kendo.all.js:7724)

We have also updated the jQuery version to the supported 3.6.0 but the error is still the same:

kendo.all.js:114061 Uncaught TypeError: r[d].get is not a function
    at r.eventResources (kendo.all.js:114061)
    at r._createEventElement (kendo.all.js:116100)
    at r._renderEvents (kendo.all.js:116221)
    at render (kendo.all.js:116300)
    at init.refresh (kendo.all.js:127143)
    at init.i (jquery-3.6.0.min.js:2)
    at init.trigger (kendo.all.js:164)
    at init._process (kendo.all.js:8137)
    at init.success (kendo.all.js:7833)
    at success (kendo.all.js:7724)

If we comment out the resources, the events are displayed correctly.

Resource is defined as follows:

resource.Add(m => m.Predmet_Id)
                  .Title("Predmet")
                  .DataTextField("Naziv")
                  .DataValueField("Id")
                  .DataColorField("Barva")
                  .DataSource(source =>
                  {
                      source.Read(read =>
                      {
                          read.Action("Predmet_Dropdown", "Predmeti");
                      })
                          .ServerFiltering(true);

                  });

I am attaching a sample data for the Scheduler.

[SrcDev]

/

[SrcDev]

The issue was that one of the resources was referring to a read.Action that had a changed URL. Although the Method had an optional parameter the initialization of the Scheduler failed without explicitly specifying the parameter.