1- Close the KNIME application
2- Find this folder: ++knime workspace++ /.metadata/.plugins/org.eclipse.e4.workbench/
3- Delete this file: workbench.xmi
4- Relaunch the KNIME application
Welcome to the KNIME community. Many thanks for sharing the bug and your found solution. I will forward this to the development team to check and fix this.
I used mac pro, you can find bellow detail version. After uninstalling the application, I followed the steps that led me to the error. I am sending the screenshots in the attached file.