Help Center/ Data Admin Service/ FAQs/ Managing connections/ What Should I Do If I Can't Connect to My RDS for MySQL Instance?
Updated on 2026-07-28 GMT+08:00
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What Should I Do If I Can't Connect to My RDS for MySQL Instance?

  1. Error message: Access denied for user 'user_name'@'100.xxx.xx.xx' (using password: YES)
    1. Error cause: The username or password of the RDS instance is incorrect.
      Solution: Check whether the username and password are correct. If you are not sure, log in to the RDS console to reset the password.

      Changing the password may affect services.

      If the username and password are correct, log in to the database using a client or CLI and run select * from mysql.user where user = 'user_name' to view the account. If 100.% (an IP address starting with 100) is assigned to a user, only the user can connect to the database through DAS. user_name @% and user_name @100.% are different users with independent passwords and permissions. Enter the password of user_name @100.%.

    2. Error cause: The IP address of the DAS server is not in the whitelist of the login user.
      Solution: Log in to the database using the client or CLI, and create a user that can be used to access the database through DAS. 
      create user 'user_name'@'100.%' identified by 'password'; 
grant select on *.* to 'user_name'@'100.%';
      • Ensure that the IP address of the DAS server is in a CIDR block starting with 100. Add the IP address to the whitelist of the login user.
      • Grant permissions to user user_name@100.% based on service requirements.
    3. Error cause: The SSL function is not enabled on the server.

      Solution: Run the following statement to check whether the user is an SSL user. If yes, enable SSL on the RDS instance details page. The user is an SSL user if the ssl_type field has a value.

      select user, host, ssl_type from mysql.user where user = 'user_name';
  2. Error message: Trying to connect with ssl, but ssl not enabled in the server

    Error cause: The SSL function is not enabled on the server.

    Solution: Run the following statement to check whether the user is an SSL user. If yes, enable SSL on the RDS instance details page. The user is an SSL user if the ssl_type field has a value. 
    select user, host, ssl_type from mysql.user where user = 'user_name';
  3. Error message: Client does not support authentication protocol requested by server. plugin type was = 'sha256_password'.
    1. Error cause: The username or password of the RDS instance is incorrect.
      Solution: Check whether the username and password are correct. If you are not sure, log in to the RDS console to reset the password.

      Changing the password may affect services.

      If the username and password are correct, log in to the database using a client or CLI and run select * from mysql.user where user = 'user_name' to view the account. If 100.% (an IP address starting with 100) is assigned to a user, only the user can connect to the database through DAS. user_name @% and user_name @100.% are different users with independent passwords and permissions. Enter the password of user_name @100.%.

    2. Error cause: The IP address of the DAS server is not in the whitelist of the login user.
      Solution: Log in to the database using the client or CLI, and create a user that can be used to access the database through DAS. 
      create user 'user_name'@'100.%' identified by 'password'; 
grant select on *.* to 'user_name'@'100.%';
      • Ensure that the IP address of the DAS server is in a CIDR block starting with 100. Add the IP address to the whitelist of the login user.
      • Grant permissions to user user_name@100.% based on service requirements.
  4. Error message: Communications link failure The last packet sent successfully to the server was 0 milliseconds ago. The driver has not received any packets from the server.

    Error cause: The network between the DAS server and the target instance is disconnected.

    Solution: Submit a service ticket to contact the customer service.

  5. Error message: Instance connect timeout, please login again

    Error cause: The connection to the DAS server timed out.

    Solution: Submit a service ticket to contact the customer service.

  6. Error information: RSA public key is not available client side (option serverRsaPublicKeyFile not set).
    Error cause: The authentication mode of the database user enforces strict password security requirements. The password transmitted over the network during authentication must be encrypted.
    • For an SSL connection, the SSL certificate and key pair are used during the TLS handshake to securely establish a symmetric key. This symmetric key is then used to encrypt the password and data.
    • For a non-SSL connection, the client encrypts the user password using the RSA public key of the MySQL server, and the server decrypts and verifies it using the corresponding RSA private key. This protects the password from interception during network transmission.

    Solution: Enable SSL for the instance or change the identity authentication mode of the database user.

Parent topic: Managing connections