value cannot be null. parameter name string

Guest User

I am stuck in this error "value cannot be null. parameter name string"

4 Replies

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Sachin Singh5y ago
Accepted answer
check your url whether your url contains something like ?Id=1 etc or not and remember querystring are case sensitive , so if you are passing parameter as capital ID then it must be in that case only while querying it in code.
+2
Ashutosh Gupta5y ago
check querystring contains ID or not before proceeding.
+1
Mageshwaran R5y ago
Pass Query String ID value,

Try this code,
protected void btnupdate_Click(object sender, EventArgs e)
{
if (Page.IsValid)
{
using (var context = new schoolDbContext())
{
var id=null;
var UserName = txtUserName.Text;
long ID=Convert.Toint64(Request.QueryString["Id"]);
if(ID>0)
{
id =ID;
}
else{
id=1;
}
var std = (from x in context.Users
where x.Id == id
select x).First();
if (std != null)
{
std.UserName = txtUserName.Text;
std.FirstName = txtFirstName.Text;
std.LastName = txtLastname.Text;
std.ClassAssigned = txtClassAssigned.Text;
std.Qualification = txtQualification.Text;
std.UserType = ddlType.SelectedValue;
std.Email = txtEmail.Text;
std.ContactNo = txtContact.Text;
context.SaveChanges();
}
}
}
}
+1
Amit Gupta5y ago
Check your query string before processing it
if(Request.QueryString["id"]!=null)
{
   //your code here
}
+1