wagon ssh / scp: No connector available to access repository ... of type default using the available factories WagonRepositoryConnectorFactory

You have a submenu layout and

<build>
  <extensions>
    <extension>
      <groupId>org.apache.maven.wagon</groupId>
      <artifactId>wagon-ssh</artifactId>
      <version>2.10</version>
  </extension>
</extensions>

Was not found while uploading! As you resolved the issue via referencing <relativePath> the parent, the wagon-ssh was finally found in the parent-pom.

By the way, if you run into this problem by mvn release and this is the only step that failed, you do not need to release again, just type mvn deploy to complete the release!

I must admit I feel slightly stupid but since others might have similar issues I am showing what resolved the issue:

<parent>
    <groupId>XXX</groupId>
    <artifactId>XXX</artifactId>
    <version>XXX-SNAPSHOT</version>
    <relativePath>../XXX/pom.xml</relativePath>
</parent>

so the pom declarations shown above where merely not being picked up at all.