Unixdude saved the day for me. I’ve been fighting with the CrashPlan service on my QNAP randomly stopping, which completely broke my home backups. I finally noticed it had been trying to auto-upgrade and failing.
This post by Unixdude describes how to manually pull in the jar files that get downloaded by the autoupgrade attempt by the headless CrashPlan instance. In my case, the most recent update included an additional .jar called bcprov-jdk15on.jar, and I had to copy that file into …/CrashPlan/lib as well.