Error when running Knime workflow in batch mode on EC2 instance: Unable to init server and Cannot open display

[Berti1989]

Hi Knime community,

I’m running into issues when trying to execute a script on an EC2 instance through the terminal window. While I have Knime properly configured to run workflows automatically via crontab at specific times, certain workflows are generating an error message if they take too long to complete. Here is the command I’m running:

<knime_directory> -nosplash -application org.knime.product.KNIME_BATCH_APPLICATION -workflowDir=‘<workflow_dir>’ -reset -nosave -workflow.variable=server_name,‘<server_name>’,String

After running for some time and completing a few nodes, I receive the following error:

INFO: LigandScout KNIME extensions shutdown complete.
Unable to init server: Could not connect: Connection refused
Knime: Cannot open display:
Knime:
JVM terminated. Exit code=4

I’m hoping someone in the community may know why this error is occurring and how I can fix it.

Thank you for your time and help!
Best regards,
Berti

[Daniel_Weikert]

Have you tried running other workflows so far and if so did they work?
br

[Berti1989]

Hi Daniel,

Yes I have, and some of them work correctly, some of them don’t. Could it be related to some nodes being deprecated? Or to the process being too long or memory consuming?

Cheers,
Berti

[Daniel_Weikert]

This might depend on what nodes you are using and how much memory you have assigned to KNIME (in case your workflows consume a lot)
Note: I am guessing I do not know just try to help here
br

[ScottF]

Maybe you can try running the workflow from the Analytics Platform instead of batch as a test? It sounds like one ore more of the nodes are failing at some point.

KNIME Batch File ERROR

Hi @gua_gunners - Exit code 2 occurs if parameters are wrong or missing. So the problem might be that you have some workflow variables that you need to provide values for. Just FYI, exit code 3 indicates when an error occurs during loading a workflow, and exit code 4 indicates if an error during execution occurred.

[Berti1989]

Thank you Daniel and Scott for your responses.
I have a GUI installed on my EC2, so what I did was to remove the “-reset” from the command I mentioned earlier and simply execute:

<knime_directory> -nosplash -application org.knime.product.KNIME_BATCH_APPLICATION -workflowDir=‘<workflow_dir>’ -reset -nosave -workflow.variable=server_name,‘<server_name>’,String

The workflow does not reset when executed, so I could satisfy myself that it had actually correctly run by opening Knime on the GUI. I guess the error exit code is due to Knime trying to open a window in the terminal and failing to do so because there is nothing to support that. But in any case I realised that there is no problem with the workflows up until they finish executing. It’s not exactly a solution, but a way around the problem

Thanks again! I’ll post on this topic if I figure out more about this error code.
Cheers,
Berti