Error while merging tables

Hello KNIME users,

I have two sets of files, one contains sd files while the other a list of properties. I am trying to join these to create a new sd file. The idea is similar to the one in the post below.

I do not want to use concatenation as the files may not have the same order, hence the use of joiner node. I get a similar error message - Unable to merge flow object stacks: Conflicting FlowObjects: <Loop Context (Head 2:6, Tail unassigned)> - iteration 0 vs. <Loop Context (Head 2:7, Tail unassigned)> - iteration 0 (loops not properly nested?)

Any help would be greatly appreciate!

Thanks in advance.

Here is how my workflow looks like.




I think that the “Java Edit Variable”-node is the reason for this error.

Do you want to create one large output file (in that case, you don’t need the “Java Edit Variable”) or do you want to create one output file per (pair of) input file(s)? In the latter case, you should try to use only one loop and move the Joiner and SDF Writer inside. For example, is it possible to combine the output of your “List Files” nodes into one table that contains pairs of files? Such a combined table could then be the basis for your single loop.

Best regards,


That is an interesting problem that you are having.  Is your data sensitive, or would it be possible to see a simple example zipped up and attached to this thread?  Joiner is definitely the node you want to use here so you are on the right track anyway. 


Aaron Hart

Hi Nils and Aaron,

thank you both for the inputs.

@Nils: I followed the latter suggestion as that was what I wanted to have. It took a little time but I finally managed to do what you suggested about creating a new table with pairs of files.

I can't thank you enough. I really appreciate it!

Here is how I did it.