simply change size of your column because you are passing larger size data than your column size for example:

your column size is : nvarchar(200) if you will try to pass 400 character then it will show the same error

Specify varchar size in SqlDBType.Varchar in C# code matching the size as specified in stored procedure eg.

cmd.Parameters.Add("@CALLING_NAME", SqlDbType.VarChar, 50).Value = callingName;

corresponding to parameter @CALLING_NAME VARCHAR(50) in stored procdeure. This ensures that size is not exceeded when being passed to stored procedure.

If length is not specified for string parameter , ADO.NET picks up arbitary length value which may exceed the size specified specified in stored procedures VARCHAR parameters.

Also at front end ensure that the number of characters being entered in textboxes doesnot exceed corresponding parameters size. This can be done using MaxLength attribute or prompting user with message using JQuery/Javascript if size exceeds.

Do it for other parameters and check.

The specified error, "String or binary data would be truncated.\r\nThe statement has been terminated." is showing when you are trying to insert a value that is higher than the specified size of the column, When we look into the given procedure we can't identify the sizes of each column, So it would better if you cross check the sizes of columns with the values that you are giving.

I can say @GENDER may cause a similar issue, since it is defined as @GENDER CHAR(1), in the procedure but you are taking a string to the method and passing as SqlDbType.VarChar instead for that you have to give the value as char. for this particular field

The String or binary data would be truncated error is telling you that you are losing data. One of the annoying things about this error is that it doesn't tell you which column(s) the problem relates to, and in a scenario like this (with lots of columns), it makes it hard to diagnose.

If you have a suitable version of SQL Server (see the following hyperlinked page), you can turn on Trace Flag 460 (this may require a restart) to tell you exactly which table and column the problem relates to.

If not, here's my more manual approach... after which there is some information about how your parameters can be silently truncated without this error (which is not good).
Notice that for each column, there is a value in a C# variable, a declared parameter type (in both the C# code and the stored proc) and the size of the column in the table (the definition of which is missing from the question - which may explain why there isn't an accepted answer yet). All of these maximum lengths and types need to tie up, for all of the columns. You really need to check all of them; but we all like shortcuts, so...

My tip for finding which column(s) are having the problem is to find a scenario where it occurs so that you can easily repeat it - this is particularly easy to do it you have a unit test of this method. Now modify the stored proc to comment out half of the columns, and try again.

• If it works, then you know the uncommented columns are fine (for this particular set of data), and the problem was in one of the columns that was commented out, so uncomment half of the lines, and try again.
• If it didn't work, then the problem is with the uncommented columns, so comment out half of the remaining columns and try again.
• Repeat until you've worked out which columns have problems. I say 'columns', because although it may only be one column having this problem, there could be more than that.
• Now put everything back as it was when you started.

Now that you've worked out which column(s) have problems check each column's definition in the table against the stored proc parameter definition, the C# parameter definition, and the value in the C# variable. You may need to track this all the way back to where the value was entered in the user interface, and ensure that suitable restrictions are in place to prevent the value being too big.
As a bonus tip, I like having unit tests that my parameter sizes correspond with the type and size of the column that they relate to. I also have constants representing the max length of each string field and the maximum value of numeric fields. These constants are unit tested against the column in the database, and are used when restricting the values given by the user in the user interface. They can also be used by the unit test of that method, to prove that inserting the largest possible value for each column actually works.

However, note that it is worth making your varchar , nvarchar and varbinary parameters larger than your column sizes due to the silent truncation that occurs with parameter coercion:

​SQL server will silently coerce your values to be whatever​ type the parameter is. For example...

DECLARE @Varchar VARCHAR(8) = 'I will be truncated';
DECLARE @Decimal92 DECIMAL(9,2) = 123.456;
DECLARE @Int INT = 123.456;
SELECT @Varchar, @Decimal92, @Int;

will output...

I will b 123.46 123

This may come as a surprise, given that SQL will complain about something like this:

BEGIN TRANSACTION;
CREATE TABLE tbl_Test(MyColumn NVARCHAR(5) NOT NULL);
INSERT INTO dbo.tbl_Test (MyColumn) VALUES (N'I will be truncated');
ROLLBACK TRANSACTION;

by saying String or binary data would be truncated. And yet the following code does not complain, silently coerces the value and inserts the record:

BEGIN TRANSACTION;
CREATE TABLE tbl_Test(MyColumn NVARCHAR(5) NOT NULL);
DECLARE @MyColumn NVARCHAR(5)=N'I will be truncated'
INSERT INTO dbo.tbl_Test (MyColumn) VALUES (@MyColumn);
ROLLBACK TRANSACTION;

So if you want to be aware of truncation issues occurring, you need to be sure that your parameter has a larger capacity than the column it is going into. For example, if we just change one character...

BEGIN TRANSACTION;
CREATE TABLE tbl_Test(MyColumn NVARCHAR(5) NOT NULL);
DECLARE @MyColumn NVARCHAR(6)=N'I will be truncated'
INSERT INTO dbo.tbl_Test (MyColumn) VALUES (@MyColumn);
ROLLBACK TRANSACTION;

...will give the truncation error. However, notice that this isn't a complete solution because if I try it with a different value...

BEGIN TRANSACTION;
CREATE TABLE tbl_Test(MyColumn NVARCHAR(5) NOT NULL);
DECLARE @MyColumn NVARCHAR(6)=N'Never complain'
INSERT INTO dbo.tbl_Test (MyColumn) VALUES (@MyColumn);
ROLLBACK TRANSACTION;

Then it will silently coerce, truncating after the space, then (because it's a varchar) the value has trailing spaces removed, and it inserts without complaining.

So the only way to be sure is to make your parameter is several characters larger than it needs to be, because there probably won't be multiple spaces in a row. You could use VARCHAR(MAX) for everything, but there is some concern that this could have performance impacts.

One place where this is particularly important is encrypted values. If encrypted values are truncated, then you can't decrypt them. So you need to be sure that your VARBINARY parameters are sized larger than the relevant column so that you would get errors instead of inserting truncated values. In this case, I believe a single character larger is sufficient, since there is no trimming of VARBINARYs. Well, apparently VarBinarys will trim trailing "nul" (ASCII=0) characters from the end; but only if ANSI_PADDING is set to OFF, but as Microsoft say, it should always be set to "ON". This section also covers what trimming occurs with different field types with different settings.

It's also worth saying that SQL isn't even consistent with how it does this. If we re-try the original example with a DECIMAL...

BEGIN TRANSACTION;
CREATE TABLE tbl_Test(MyColumn DECIMAL(9,2) NOT NULL);
INSERT INTO dbo.tbl_Test (MyColumn) VALUES (123.456);
SELECT * FROM tbl_Test
ROLLBACK TRANSACTION;

It doesn't complain about the value having too many decimal places, it just silently coerces it. And the same is true if I do it through a parameter which has more decimal places than the column...

BEGIN TRANSACTION;
CREATE TABLE tbl_Test(MyColumn DECIMAL(9,2) NOT NULL);
DECLARE @MyColumn DECIMAL(9,3)=123.456
SELECT @MyColumn
INSERT INTO dbo.tbl_Test (MyColumn) VALUES (@MyColumn);
SELECT * FROM tbl_Test
ROLLBACK TRANSACTION;

And yet if I give it a value that is too large...

BEGIN TRANSACTION;
CREATE TABLE tbl_Test(MyColumn DECIMAL(9,2) NOT NULL);
INSERT INTO dbo.tbl_Test (MyColumn) VALUES (1234567890.456);
SELECT * FROM tbl_Test
ROLLBACK TRANSACTION;

Then it will complain with Arithmetic overflow error converting numeric to data type numeric. (as it would if I put that value into a parameter first).

One other thing to mention relates to parameter coercion and encryption. Imagine a scenario where you have an SQL column typed DECIMAL(9,2) and a parameter of the same type, and you are giving it a dot net "decimal" from your C# code. If the "decimal" in your code has lots of decimal places, this silent coercion will effectively be asking SQL to do the rounding for you. Which is fine... Until you decide to encrypt that column, because now the value you are encrypting would be a much longer value than the SQL DECIMAL column would have been able to hold, so is probably larger than you have allowed (in terms of your VARBINARY length). In this scenario you would need to ensure the value was rounded to the correct number of decimal places before encryption.

On the trimming trailing space of the parameter. It is only trimming as much as it needs... this shows that it has trimmed one space from the parameter, but left the remaining 4 after the N.

BEGIN TRANSACTION; 
CREATE TABLE tbl_Test(MyColumn NVARCHAR(5) NOT NULL); 
DECLARE @MyColumn NVARCHAR(6)=N'N     complain' 
SELECT @MyColumn +'|',LEN(@MyColumn),DATALENGTH(@MyColumn) 
INSERT INTO dbo.tbl_Test (MyColumn) VALUES (@MyColumn); 
SELECT MyColumn +'|',LEN(MyColumn),DATALENGTH(MyColumn) FROM dbo.tbl_Test 
ROLLBACK TRANSACTION;

Yet another learning point about this... the same concept applies to user defined table types which correlate to table definitions.

Here is an example script to demonstrate the issue. Notice that the creation and dropping of the type has to be done outside the transaction.

CREATE TYPE dbo.MyTableType AS TABLE (MyColumn NVARCHAR(5) NOT NULL); 
GO 
BEGIN TRANSACTION; 
DECLARE @MyColumn NVARCHAR(5)=N'I will be truncated' 
DECLARE @MyTable AS dbo.MyTableType; 
INSERT INTO @MyTable (MyColumn) VALUES (@MyColumn); 
CREATE TABLE dbo.tbl_Test (MyColumn NVARCHAR(5) NOT NULL); 
INSERT INTO dbo.tbl_Test SELECT MyColumn FROM @MyTable; 
ROLLBACK TRANSACTION; 
GO 
DROP TYPE dbo.MyTableType;

I have few suggestions to identify this: (Choose any 1, and then move to other, if issue still exists. Order doesn't matter, which ever Suggestion, you fell easy).

• Suggestion 1: Open the sql profiler and track the requests. Get the query from profiler and run it directly on SQL Server. you may get more details of error.

Steps:

• Start debugging, and stop just before you are going to call the db.

• Open Profiler, connect to DB.

• Click on Clear Trace Window.

• Start the debugging.

• Stop the profiler, as soon as you got few requests.

• Identify the Query, and run on SQL Server.
  

• Suggestion 2: Try to Insert data using SQL Server management studio.
  Steps:

• Right click on table -> Click on Script Table as -> Insert To.

• Now, compare with your Input, if you are passing correctly.

• Suggestion 3: Use this code to get the difference between data length and data passed or directly truncate when passing to DB.
  Steps:

• Create this Class DbContextExtension .

using System;
using System.Collections.Generic;
using System.Linq;
using Microsoft.EntityFrameworkCore;
using Microsoft.EntityFrameworkCore.Metadata;

namespace Data.Context
{
    public class DbContextExtension
    {
        private Dictionary<IProperty, int> _maxLengthMetadataCache;

        public void AutoTruncateStringToMaxLength(DbContext db)
        {
            var entries = db?.ChangeTracker?.Entries();
            if (entries == null)
            {
                return;
            }

            var maxLengthMetadata = PopulateMaxLengthMetadataCache(db);

            foreach (var entry in entries)
            {
                var propertyValues = entry.CurrentValues.Properties.Where(p => p.ClrType == typeof(string));

                foreach (var prop in propertyValues)
                {
                    if (entry.CurrentValues[prop.Name] != null)
                    {
                        var stringValue = entry.CurrentValues[prop.Name].ToString();
                        if (maxLengthMetadata.ContainsKey(prop))
                        {
                            var maxLength = maxLengthMetadata[prop];
                            stringValue = TruncateString(stringValue, maxLength);
                        }

                        entry.CurrentValues[prop.Name] = stringValue;
                    }
                }
            }
        }

        private Dictionary<IProperty, int> PopulateMaxLengthMetadataCache(DbContext db)
        {
            _maxLengthMetadataCache ??= new Dictionary<IProperty, int>();

            var entities = db.Model.GetEntityTypes();
            foreach (var entityType in entities)
            {
                foreach (var property in entityType.GetProperties())
                {
                    var annotation = property.GetAnnotations().FirstOrDefault(a => a.Name == "MaxLength");
                    if (annotation != null)
                    {
                        var maxLength = Convert.ToInt32(annotation.Value);
                        if (maxLength > 0 && !_maxLengthMetadataCache.ContainsKey(property))
                        {
                            _maxLengthMetadataCache[property] = maxLength;
                        }
                    }
                }
            }
            
            return _maxLengthMetadataCache;
        }

        private static string TruncateString(string value, int maxLength)
        {
            if (string.IsNullOrEmpty(value)) return value;
            return value.Length <= maxLength ? value : value.Substring(0, maxLength);
        }
    }
}

• Use it like this, before calling your SaveChanges:

public class DocumentRepository : IDocumentRepository 
    {
        private readonly DbContext _context;
        public DocumentRepository(DbContext context)
        {
            _context = context;
        }

        public async Task CreateDocument(Document obj)
        {
            //Feel free to make it extension method or use it as DI. To make the example easier, I am creating the object here.
            var dbExtensions = new DbContextExtension();
            dbExtensions.AutoTruncateStringToMaxLength(_context);
            await _context.Documents.AddAsync(obj);
            await _context.SaveChangesAsync();
        }