Why Am I Getting the \'Unrecognized SSL Message, Plaintext Connection?\' Error in Java?

Exception: "Unrecognized SSL Message, Plaintext Connection?

The error "Unrecognized SSL message, plaintext connection?" arises when attempting to establish a connection with an HTTPS server using a Java package. This exception indicates a mismatch between the expected secure connection and the actual plaintext connection.

Cause:

The exception occurs due to a failure to establish a secure SSL/TLS connection with the server. The underlying cause may be that the connection is not configured for HTTPS, using an incorrect port number or that there are trust issues with the server's certificate.

Solution:

To resolve this issue, verify the following:

• Check the port number: Ensure that you are using the correct port number for HTTPS, typically 443.
• Enable SSL/TLS on the server: Verify that the HTTPS server is properly configured to accept SSL/TLS connections.
• Check CA certificates: Ensure that the server's certificate is signed by a trusted Certificate Authority (CA) and that the CA's certificate is installed on the client machine.
• Disable plaintext connections: If possible, disable the option to accept plaintext connections on the server, as they are insecure.

By ensuring that the connection is configured correctly and that the necessary certificates are installed, you can establish a secure connection with the HTTPS server and resolve the "Unrecognized SSL message" exception.

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