Stored procedure doesn't allow null parameters even the parameter represent accept nulls?

Question

I saw many questions on stack overflow, non of them touched my own problem

procedure or function expects parameter which was not supplied

Answer 1

I just found that I can set default values for the parameter in the stored procedure:

ALTER proc [dbo].[spAddCustomer]
@cuName varchar(50)=null,
@cuAddress varchar(50)=null,
@cuMobile varchar(50)= null,
@cuImage image= null,
@cityId int= null,
@exist int output

And this solved my problem! This is helpful specifically with null images from the PictureBox, since I have a helper method that checks for empty strings.