Hi Guys,

I recently found this and thought I'd share it with you, in case anybody else also comes across it.[I couldn't find it in a quick search already]

I had a usercontrol in the backend site which was using the query string:

?delete=somestringidentifier 

This started to cause problems, when the string was not numeric, the action was not being carried out as expected, and throwing errors.

I quickly tracked it down to KeyValuePrevalueEditor.cs in umbraco.editorControls.KeyValuePrevalueEditor - you can guess what's coming... I found this code:

// Bootstrap delete.
if (System.Web.HttpContext.Current.Request["delete"] != null) {
    DeletePrevalue(int.Parse(System.Web.HttpContext.Current.Request["delete"]));
    }
}

private void DeletePrevalue(int id) {
    SqlHelper.ExecuteNonQuery("delete from cmsDataTypePreValues where id = " + id);
}

Looks like my choice of querystring has already been taken!! A string value wouldn't cast to an integer and threw an exception!

Quick fix: Change your query string!!

Hopefully this should help someone else out, by either avoiding this in the first place, or looking for the solution using the search.