IDX10503: Signature validation failed

Securing applications
1

when i tried to validate JWT token sometimes i get an “Signature validation failed.” and again tried to same token, When I try again, token validation is successful. This problem happens all the time. Validation method is below. If anyone has experienced this situation before, can they give an idea about the solution?

..
        var rsaParameters = new RSAParameters
        {
            Modulus = Base64UrlEncoder.DecodeBytes(keys[0]["n"].ToString()),
            Exponent = Base64UrlEncoder.DecodeBytes(keys[0]["e"].ToString())
        };

        using var rsa = RSA.Create();
        rsa.ImportParameters(rsaParameters);

        var validationParameters = new TokenValidationParameters
        {
            ValidateIssuerSigningKey = true,
            IssuerSigningKey = new RsaSecurityKey(rsa),
            ValidateIssuer = false,
            ValidateAudience = false
        };

        var tokenHandler = new JwtSecurityTokenHandler();
        tokenHandler.ValidateToken(_token, validationParameters, out _);

    ..
}```
2

I add below 2 lines inside of validationParameters, that validation is runs correct,
IssuerSigningKeys = new List() { new RsaSecurityKey(rsa) },
TryAllIssuerSigningKeys = true,

hole code block below,

…
var rsaParameters = new RSAParameters
{
Modulus = Base64UrlEncoder.DecodeBytes(keys[0][“n”].ToString()),
Exponent = Base64UrlEncoder.DecodeBytes(keys[0][“e”].ToString())
};

using var rsa = RSA.Create();
rsa.ImportParameters(rsaParameters);

var validationParameters = new TokenValidationParameters
{
ValidateIssuerSigningKey = true,
TryAllIssuerSigningKeys = true,
IssuerSigningKey = new RsaSecurityKey(rsa),
IssuerSigningKeys = new List() { new RsaSecurityKey(rsa) },
ValidateIssuer = false,
ValidateAudience = false
};

var tokenHandler = new JwtSecurityTokenHandler();
tokenHandler.ValidateToken(_token, validationParameters, out _);
…