An unhandled exception of type 'System.ArgumentNullException' occurred

Question

An unhandled exception of type 'System.ArgumentNullException' occurred in mscorlib.dll

Additional information: Value cannot be null.

for this:

var flags = uint.Parse((string)checkedRadioButton.Tag, System.Globalization.NumberStyles.HexNumber);

Naveen · Answer

Hi Yogi, RadioButton checkedRadioButton = groupBoxRegistrationFlag.Controls.OfType ().FirstOrDefault(r => r.Checked); var flags = uint.Parse((string)checkedRadioButton.Tag, System.Globalization.NumberStyles.HexNumber); check this. Thanks!

Yogi S · Answer

The flags variable did not find checkedRadioButton so you get this error. Put breakpoint and see the full message and post it here so that we can understand more on it.

Amit Mohanty · Answer

The issue is occurring because checkedRadioButton is null, meaning no radio button is currently checked in the groupBoxRegistrationFlag.Controls collection. You should check if checkedRadioButton is not null before attempting to access its properties. RadioButton checkedRadioButton = groupBoxRegistrationFlag.Controls.OfType ().FirstOrDefault(r => r.Checked); if (checkedRadioButton != null) { var flags = uint.Parse((string)checkedRadioButton.Tag, System.Globalization.NumberStyles.HexNumber); } else { // You can throw an exception, provide a default value, or take any other appropriate action }