RSA decryption error: the data to be decrypted exceeds the maximum 128 bytes of this module

            RSACryptoServiceProvider rsa = new RSACryptoServiceProvider();
            byte[] cipherbytes;
            rsa.FromXmlString(privatekey);
            cipherbytes = rsa.Decrypt(Encoding.UTF8.GetBytes(content), false);
            var Text=Encoding.UTF8.GetString(cipherbytes);

cipherbytes = rsa.Decrypt(Encoding.UTF8.GetBytes(content), false);
Modify to:
cipherbytes = rsa.Decrypt(Convert.FromBase64String(content), false);