Transformers cannot loop over list elements

Hi RMG and all other Experts,

I have a loop running on one of my document reference and in a loop i am using MAP to substring perticular value and then mapping it back to same document reference variable. But i don’t know why i am getting this exception. Appreciate your help on this.

java.lang.RuntimeException: [ISC.0049.9027] Error at pub.string:substring - Transformers cannot loop over list elements

I have also attached the mapping image for reference.

mapping Exception.jpg

The error reason is in your MAP step when you map the transformer (substring) click on the link Properties and make sure the pipelineIn clientNumber field is not expecting Index there…If it is then set 0 and save it.(You shouldn’t have Index here since you are already inside loop of recordWithNoID) somehow your InArray path is not working…

But since the mapping field is part of the Loop documentList InArray (for recordWithNoID) then unmap link to the substring and just shift out and shift in the map step and then link the clientNumber to substring and again make sure the Index is not there…Cross check the same thing where ever you use transformers esp from a docList/fields.



Thanks for the reply. I tried ur suggestion but getting the same error.

Can you please suggest me wome workaround.

Thanks, Appreciated.



From the image attached in your post, it shows that you are not actually looping over GoodCustomers/recordWithNoID. Show your loop. You should have a loop step, in array should be GoodCustomers/recordWithNoID and a map step should be indented under the loop – this substring should work after that



Yes use a Loop step set InArray (GoodCustomers/recordWithNoID) and inside the Loop put all your map steps and re-link the recordWithNoID fields…this is what i am trying to say above.

This will solve the problem…


hi atul,

services should NOT be used as transformers inside any loop.
call the service explicitly and ur problem should be resolved.


We can use transformers inside any loop…just we have to make sure always the loop documentlist show as doc inside the map step and when you link the transformer input you should not see any Index to be set in the map link properties section.If yes then loop on document is not working and thus you will get the error above.


Similar problem for me.
I did indent the Transformer MAP under a LOOP, but still get following error

java.lang.RuntimeException: [ISC.0049.9027] Error at - Transformers cannot loop over list elements

Any workaround?