Error when using knimepy from jupyter

KNIME Extensions
2

Hi MagAmine –

From what you describe for this particular error, the chronological sequence of events sounds like:

  1. The Container Output (Table) node encountered a problem during the workflow execution and was unable to produce any output.
  2. KNIME finished execution of the workflow.
  3. The knimepy module’s code complained that it could not find any output from the Container Output (Table) node.

Tracing this backwards, given your workflow SVG (thanks for providing), a couple of possibilities pop into my mind:

  • Could there really be write-permissions problem on disk? (I would be surprised but the thought did occur.)
  • Did the problem originate in the Container Input (Table) node but its complaint appears much earlier in the KNIME log which does not automatically get shared through Jupyter? (I think this much more likely.)

A couple of options for how to investigate this further:

  1. Looking through KNIME’s knime.log before this error occurs may help identify what led up to it.
  2. Try running again but enable the option wf.execute(live_passthru_stdout_stderr=True) to see more in Jupyter of the KNIME execution’s logging than just the final error.
  3. Try changing wf.save_after_execution to True and then after the failed execution, open the workflow in KNIME again to see its final state – you can then investigate the final state of the various nodes through KNIME in the usual way.

I have a suspicion that the Container Input (Table) node did not properly receive your pandas DataFrame from Python but because you have a default (so-to-speak) input connected to that node, it was relatively quiet about the problem – as to why or what really happened next, I am unsure but I hope the above suggested paths forward help clear things up quickly. I will be interested to hear what you find.

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