JWT Encryption Error when using EncryptingCredentials in token generation method - asp.net-core

Question

I implemented JWT token in my ASP.net core 3.1 web api.
In the token generation method when I try to use EncryptingCredentials I got the below error :
IDX10662: The KeyWrap algorithm 'System.String' requires a key size of 'System.Int32' bits. Key '', is of size:'System.Int32'. (Parameter 'Length')
This is my Token generation method :
public async Task<string> GenerateAsync(User user)
{
var secretKey = Encoding.UTF8.GetBytes(_siteSetting.JwtSettings.SecretKey); //"SampleSecretKeyChange"
var signingCredentials = new SigningCredentials(new SymmetricSecurityKey(secretKey), SecurityAlgorithms.HmacSha256Signature);
var encryptionkey = Encoding.UTF8.GetBytes(_siteSetting.JwtSettings.Encryptkey); //"AbcdefgHijklmnopk123456"
var encryptingCredentials = new EncryptingCredentials(new SymmetricSecurityKey(encryptionkey), SecurityAlgorithms.Aes128KW, SecurityAlgorithms.Aes128CbcHmacSha256);
var descriptor = new SecurityTokenDescriptor
{
Issuer = _siteSetting.JwtSettings.Issuer,
Audience = _siteSetting.JwtSettings.Audience,
IssuedAt = DateTime.Now,
NotBefore = DateTime.Now.AddMinutes(_siteSetting.JwtSettings.NotBeforeMinutes),
Expires = DateTime.Now.AddMinutes(_siteSetting.JwtSettings.ExpirationMinutes),
SigningCredentials = signingCredentials,
EncryptingCredentials = encryptingCredentials,
Subject = new ClaimsIdentity(_getClaims(user))
};
var tokenHandler = new JwtSecurityTokenHandler();
var securityToken = tokenHandler.CreateToken(descriptor);
var jwt = tokenHandler.WriteToken(securityToken);
return await Task.FromResult(jwt);
}

Answer 1

After of all research that I did, I found the problem. When you want to use EncryptingCredentials with the conditions that I described the Encryptkey key length must be equal 16 characters.