You're showing exactly the troubled config that I've been explaining to you. You need to add leading / to the url.

Those URLs are different, you're talking about redirection rules. Your ASP.NET backend is looking for ganttcrud method on the Main controller, according to the URL /Main/ganttcrud/load. Just open this URL in browser and you'll see. And then open same URL without leading Main/.

It looks like you have wrong configuration for project load url, it should be smth like:

project : {
  transport : {
    load : { url  : '/ganttcrud/load' } // it should start with a slash specifying global URL
  }
}

Hello Daniel.
This is a known problem, please see this issue for a workaround: https://github.com/bryntum/support/issues/2215

Hello.
This looks like a duplicated thread, please see my response here: viewtopic.php?p=81530#p81530 and lets move discussion there too.

Hello.
Reproduced, ticket opened here: https://github.com/bryntum/support/issues/2234 Thank you for report.

To work around this issue please update model definition:

// app/lib/models/Task.js
...
{ name: 'effortUnit', dataSource: 'EffortUnit', convert(value) { return value || 'hour' } },
...