Hello guys,
I need to add SharePoint-hosted add-in in document set new form "NewDocSet.aspx" and since this is not possible because it is application page i am trying to replace the default with my custom webpart page "WPPT.aspx". Threw SharePoint
designer i am able to change the new form page of an chosen content type.
When i click on the new doc set of this content type the page is redirected to this web part page:

There is a lot of information appended in the query string by SharePoint when the page gets redirected and that is ok.
But there is one single query parameter that breaks the page and my custom web part page cannot be loaded:


When i modify "List=364abd2b-4348-4d9e-a816-455796e58540" to
"List=364abd2b-4348-4d9e-a816-455796" or whatever else id ot this list query parameter it works fine.
My question is why the page brakes when this list query parameter exists and points to real list. What can i do to remove it or at least to not breaking my custom web-part page. SharePoint is trying to use this information to do something but i am not sure
what is doing.
I will appreciate any feedback,
Thank you in advance!
Jordan Georgiev