Hello Denis,
Looks as if you ran into the incompatibility problem of the latest open jdk version with older KNIME server versions: Java update 8u242 breaks execution with RMI executors
Depending on your version you can update your server to the latest build of it, please find update instructions for the 4.10.3 release here: https://docs.knime.com/2019-12/server_update_guide/index.html
For older releases please navigate to the right guide starting from the main documentation site:
https://docs.knime.com
All downloads are linked here:
https://www.knime.com/knimecom-product-downloads
Cheers,
Michael