I am currently working on an ASP.NET MVC web application using DevExpress controls and I ran into a very annoying issue that I could not fix so far.
I am implementing a page/view which consists of multiple partial views. One of those partial views contains a DevExpress GridView control which contains a so called "DetailRow". This detail row is meant to show additional information about a row when clicking on a small "+" button on the left side of each row. I already use a very similar (basically almost identical) GridView inside of a DevExpress "PopupControl" on another page of my website without any problems, but on the new page I am currently working on it just does not work.
The page actually loads just fine when I open it, but as soon as I click on the small "+" in a row my controller's Index-method is called and I do not understand why. On the other page which has the GridView inside a PopupControl, only the method for the partial which contains the GridView and the method for the actual content of the DetailRow is called, which is what I would expect to happen on my new page as well.
I have already recorded the network communication between the site and the server and I do not see any GET request either which would result in the Index-method getting called. There is only a POST for the partial which contains the GridView. I also get the following DevExpress-specific error logged in the console when this happens:
Invalid server response. It is required that a Partial View contains only the extension definition code, without any additional markup. To learn more, see https://www.devexpress.com/kbid=KA20010.
Unfortunately the linked article in that error did not help me figure out the problem either. It talks about making sure that all extensions are defined in a separate PartialView with no extra tags but I already have it like that, there are no extra tags anywhere in my partial views. I also do not assign a unique SettingsBase.Name value so that cannot be the problem either.
Does anyone know what is going wrong here or how I can further debug the problem? I do not know any way of finding out why the Index-method of my controller is being called so I have no clue what to do.
