Since you're posting, do not send the data as if you're using GET. Set the fixed path
/Usermanagement/AdProxyGroupMapping and then use
"data: " to send what you need
like this:
strSelecteds = strSelecteds.substring(0, strSelecteds.length - 1);
$.ajax({
url: "/Usermanagement/AddProxyGroupMapping",
type: 'POST',
data: {'jsonValue': strSelecteds, 'IsInsert': IsInsert, 'PackageId': packageId, 'Allocate': Allocate }
contentType: 'application/json;charset=utf-8'
});
You might need to tweak this, data needs to be JSON, maybe I misspelled something, but sending long query string (which is limited to around 2000 characters in IE and 4000 total) is not a good idea.
Since you are using POST method, send the data as for post.
If this helps please take time to accept the solution. Thank you.