Why does my Maven deploy fail with a fatal alert for protocol version?

Issue

Deploying with the Heroku Maven plugins fails with an error like:

[ERROR] Failed to execute goal com.heroku.sdk:heroku-maven-plugin:1.2.0:deploy (default-cli) on project helloworld: Failed to deploy application: Received fatal alert: protocol_version -> [Help 1]

Resolution

This error happens because your locally Java environment is trying to connect to the Heroku API with TLS v1.0, which is no longer supported. You'll need to update your local Java Development Kit (JDK) to either Java 8 or a newer build of Java 7.

Oracle has ended its support for Java 7 and no longer provides public updates. However, you can use the open source Zulu distribution from Azul (which is built from OpenJDK) if you wish to remain on Java 7.