Ext Js API POST Success function is not executed even when the data is posted

I am using ASP .Net Web Application Web Api and Ext JS as my UI
I dont know what seems to be the problem why my success function is not being executed but the error of failure is even when the data itself is posted and added in the database
the logs also shows that its the failure only that is executed here

this is the grid js
where when save is clicked the api linked is called and the method post

tbar: [
{
  text: "Add Movie",
  iconCls: "fa fa-plus",
  handler: function () {
    Ext.create("Ext.window.Window", {
      title: "Add Movie",
      modal: true,
      items: [
        {
          xtype: "form",
          bodyPadding: 10,
          defaultType: "textfield",
          defaults: {
            anchor: "100%",
            labelWidth: 100,
          },
          items: [
            {
              fieldLabel: "Name",
              name: "name",
              allowBlank: false,
            },
            {
              fieldLabel: "Description",
              name: "description",
              xtype: "textarea",
              allowBlank: false,
            },
            {
              fieldLabel: "Available",
              name: "available",
              xtype: "numberfield",
              allowBlank: false,
              regex: /^[0-9]+$/,
              regexText: "Only numeric values are allowed",
            },
          ],
          buttons: [
            {
              text: 'Save',
              formBind: true,
              handler: function () {
                var form = this.up('form').getForm();
                if (form.isValid()) {
                  console.log('Before form submit');
                  form.submit({
                    url: 'https://localhost:44345/api/movies',
                    method: 'POST',
                    success: function (form, action) {
                      console.log('Success: ', action.response.responseText);
                      try {
                        var jsonData = JSON.parse(action.response.responseText);
                        console.log('Valid JSON:', jsonData);
                        // Handle the successful response
                        Ext.Msg.alert('Success', 'Movie saved successfully');
                        form.reset();
                      } catch (error) {
                        console.log('Invalid JSON:', error);
                        // Handle the invalid JSON response
                        Ext.Msg.alert('Error', 'Invalid JSON response');
                      }
                    },
                    failure: function (form, action) {
                      console.log('Failure: ', action.response.responseText);
                      // Handle the failure response
                      Ext.Msg.alert('Error', 'Failed to save the movie');
                    }
                  });
                }
              }
            }
            ,
            {
              text: "Cancel",
              handler: function () {
                this.up("window").close();
              },
            },
          ],
        },
      ],
    }).show();
  },
},

],

and here is my post method in the api

public IHttpActionResult Post([FromBody] Movies movieDto)
    {
        if (!ModelState.IsValid)
            return BadRequest(ModelState);

        var movie = new Movies
        {
            Name = movieDto.Name,
            Description = movieDto.Description,
            Available = movieDto.Available
            // Set other properties as needed
        };

        _dbContext.Movies.Add(movie);
        _dbContext.SaveChanges();

        // Return the created movie with its assigned ID
        movieDto.Id = movie.Id;
        return Created(Request.RequestUri + "/" + movieDto.Id, movieDto);
    }

Ext.form.Basic.submit method requires the API to return the following response to indicate a successful operation:

{
    "success":true, // note this is Boolean, not string
    "msg":"Consignment updated"
}

So the HTTP 201 Created is not enough, you also have to send a JSON with success property set to true.

Please also check the documentation here. You could look into custom reader and writer if you want to change this behaviour but it might be easier to change the API.