Java update 8u242 breaks execution with RMI executors

The recent update of Java to 8u242 on Ubuntu breaks execution of workflows using RMI executors (which still is the default execution mode right now). We have identified the problem and are currently working on a fix and will release it as soon as possible. Until then please don’t update Java if possible! If you already updated and your server isn’t working any more, downgrade to the previous version (everything before 8u241 will work).

  • On Windows uninstall the current version and install a previous one. If you still have that installed you can also simply change the path to the JRE in the service.
  • On Ubuntu first determine what previous version is available using apt-cache showpkg openjdk-8-jdk-headless. This usually outputs the currently installed version and at least one previous version, e.g. 8u242-b08-0ubuntu3~18.04 and 8u162-b12-1. Take the lower version and install it explicitly using apt install openjdk-8-jdk=8u162-b12-1 openjdk-8-jdk-headless=8u162-b12-1 openjdk-8-jre-headless=8u162-b12-1 openjdk-8-jre=8u162-b12-1 or similar.
  • For RHEL/CentOS the affected Java version isn’t available yet. In case you read this post after you have updated to the affected Java version you can downgrade using yum downgrade java-1.8.0-openjdk- or similar.

Since today the Java update is also offered for CentOS (7). Do not install this update yet!
We have fixed the issue and will release an updated version of KNIME Server 4.10, 4.9, and 4.8 next week.


We have released updates for KNIME Server 4.8, 4.9, and 4.10 yesterday that fix the problem. You can get them for the normal download pages. After applying them it’s safe to update Java to the latest version.