It seems that the "Environment Name" field in the "Application and Environment" section is required, not optional as expected. The help tooltip and documentation both indicate it should be optional. If an environment name is not specified, the plugin should just upload the new EB application version.

Optional: AWS EB Environment Name for the Application (e.g.: "myapp-prod-env"). When set and Environment Name exists, it will trigger a UpdateEnvironment Call when the Application Version is created.

This plugin does steps 1-3 and if an environment name is specified and its active, it also does the UpdateEnvironment API call.

This is the error when the job runs:

java.io.IOException: Deployment Failure
at br.com.ingenieux.jenkins.plugins.awsebdeployment.AWSEBDeploymentBuilder.perform(AWSEBDeploymentBuilder.java:171)
at hudson.tasks.BuildStepMonitor$1.perform(BuildStepMonitor.java:20)
at hudson.model.AbstractBuild$AbstractBuildExecution.perform(AbstractBuild.java:782)
at hudson.model.Build$BuildExecution.build(Build.java:205)
at hudson.model.Build$BuildExecution.doRun(Build.java:162)
at hudson.model.AbstractBuild$AbstractBuildExecution.run(AbstractBuild.java:534)
at hudson.model.Run.execute(Run.java:1738)
at hudson.model.FreeStyleBuild.run(FreeStyleBuild.java:43)
at hudson.model.ResourceController.execute(ResourceController.java:98)
at hudson.model.Executor.run(Executor.java:410)
Caused by: java.util.concurrent.ExecutionException: java.lang.IllegalArgumentException: Empty/blank environmentName parameter
at java.util.concurrent.FutureTask.report(Unknown Source)
at java.util.concurrent.FutureTask.get(Unknown Source)
at hudson.remoting.LocalChannel$2.get(LocalChannel.java:77)
at br.com.ingenieux.jenkins.plugins.awsebdeployment.DeployerRunner.perform(DeployerRunner.java:66)
at br.com.ingenieux.jenkins.plugins.awsebdeployment.AWSEBDeploymentBuilder.perform(AWSEBDeploymentBuilder.java:167)
... 9 more

This is the error when "Validate Coordinates" is clicked in the build step config:

javax.servlet.ServletException: com.amazonaws.AmazonServiceException: 1 validation error detected: Value '[]' at 'environmentNames' failed to satisfy constraint: Member must satisfy constraint: [Member must have length less than or equal to 40, Member must have length greater than or equal to 4]