SES SMTP mail giving openssl :EVP_CIPHER_CTX_set_key_length:invalid key length Error

Question

We are creating Yii2 Rest API. We are implementing SES SMTP. Email is working fine but With API Response, We are getting 500 Internal Server Error with below Fetal Error:

"Uncaught exception 'yii\base\ErrorException' with message 'fgets(): SSL operation failed with code 1. OpenSSL Error messages: error:0607A082:digital envelope routines:EVP_CIPHER_CTX_set_key_length:invalid key length"

Complete Error Message coming as below:

Fatal error: Uncaught exception 'yii\base\ErrorException' with message 'fgets(): SSL operation failed with code 1. OpenSSL Error messages: error:0607A082:digital envelope routines:EVP_CIPHER_CTX_set_key_length:invalid key length' in /var/www/html/rington/advanced/vendor/swiftmailer/swiftmailer/lib/classes/Swift/Transport/StreamBuffer.php:163 Stack trace: #0 [internal function]: yii\base\ErrorHandler->handleError(2, 'fgets(): SSL op...', '/var/www/html/r...', 163, Array) #1 /var/www/html/rington/advanced/vendor/swiftmailer/swiftmailer/lib/classes/Swift/Transport/StreamBuffer.php(163): fgets(Resource id #31) #2 /var/www/html/rington/advanced/vendor/swiftmailer/swiftmailer/lib/classes/Swift/Transport/AbstractSmtpTransport.php(397): Swift_Transport_StreamBuffer->readLine(40) #3 /var/www/html/rington/advanced/vendor/swiftmailer/swiftmailer/lib/classes/Swift/Transport/AbstractSmtpTransport.php(277): Swift_Transport_AbstractSmtpTransport->_getFullResponse(40) #4 /var/www/html/rington/advanced/vendor/swiftmailer/swiftmailer/lib/c in /var/www/html/rington/advanced/vendor/swiftmailer/swiftmailer/lib/classes/Swift/Transport/StreamBuffer.php on line 163

I have tried different Solution given on Google Search but nothing works.

Please help.

Thanks in advance.