Renderer To Image returning an Error: Execute failed: ("NullPointerException"): null

Hi All,

I’ve got a workflow that takes a table with ~20,000 SDF molecular structures (one per row) and converts these to PNG images using the ‘Renderer to Image’ node (using the Marvin renderer). This has worked successfully for several years but recently the node has been failing and returning the following error:
“Execute failed: (“NullPointerException”): null”
I’ve ensured that there are no cells with missing data so that doesn’t seem to be the problem. Does anyone have an idea of how to resolve this?

Thanks in advance,


Hi Mike,

could you please elaborate on this:

  • was it a one time failure or is it constantly failing since the first occurence?
  • which version of the Analytics Platform (AP) are you using?
  • how many heapspace is assigned to the KNIME AP? This is configured via the -Xmx parameter in the knime.ini

Were there additional errors recorded in the knime logfile?

Thanks in advance,

Hi Michael,

Please see below for the responses to your questions:

  1. It is constantly failing since the first occurrence of this error message (this is a scheduled workflow on the knime server)
  2. We’re currently using KNIME AP version 3.7.2 with uor KNIME server. Yes, I know we should update to the latest version but this involves lots of testing of all the production workflows which we currently don’t have the resources to complete)
  3. It’s installed on a fairly beefy machine: -Xmx256G

Thanks in advance for your help!