Restarting KNIME fixes the problem until you try to repeat the action. So, it worked once and then I rerun the workflow and get the error.
Attach the logfileKnimeLog_afterReboot.txt (56.0 KB)
Further info. It seems there was a part of the workflow that did not run correctly and generated an empty cell in an SDF column. However, the task and workflow completed successfully.
After resetting that workflow and rerunning it, I do not have errors anymore.