Nested loop node is not working as expected when its run for the second time

[TrinhNhatHuy]

Hello everyone,
I am running n8n locally on my laptop using Docker and am currently developing a workflow that listens for incoming emails, downloads an attached Excel file, and extracts data from it.
The Excel file contains program schedules for a TV channel over one year:

• Each sheet represents one month
• Each month contains multiple days
• Each day has its own program schedule
  Workflow Logic:
• The first loop iterates through each sheet (month)
• The second loop iterates through each day within a month and extracts that day’s program schedule
  Problem:
• The workflow works correctly for the first month and extracts the data as expected.
• When processing the second month, the data from the first loop is still extracted correctly.
• However, the data passed into the second loop immediately goes to the “Done” branch, which causes unexpected behavior.
• As a result, I cannot extract the program schedules for the second month.
  Question:
• I am considering using a sub-workflow to solve this issue, but I am unsure:
  Where should I place the “Execute Sub-Workflow” node in my current workflow?
  Are there any alternative approaches that would be more suitable for this scenario?
  Thank you very much for your time and help. I would really appreciate any guidance or suggestions.

Describe the problem/error/question

What is the error message (if any)?

Please share your workflow

Share the output returned by the last node

Information on your n8n setup

• n8n version: 1.112.5
• Database (default: SQLite):
• n8n EXECUTIONS_PROCESS setting (default: own, main):
• Running n8n via (Docker, npm, n8n cloud, desktop app):docker
• Operating system: windows

[solomon]

I’ve also observed this behavior with one of the members in my community.

@TrinhNhatHuy Would you be so kind to pin some data to your nodes so I can replicate this on my end without having to connect to any data source, please?

@Jon This is likely a bug.

[TrinhNhatHuy]

[TrinhNhatHuy]

@solomon thank you for your help. Im very willing to provide you as much information as i can. Please tell me if you need any further infor.

[Parintele_Damaskin]

Hey @TrinhNhatHuy and @solomon !

Isn’t this the “classic” nested loop in smae workflow ?(can’t test since am am not at PC)…

But found this topic from Jon where explains a “trick” about this… but the recommended way still remains the subworkflow.

Loop Node Only Processes the First Item - How to Fix?

Hey @Gustavo_Borges, I have just picked this one up, The loop node can be tricky at times. So in this case the reset option needs to be used to tell the Loop node that it is a new set of data but as you probably noticed while testing if you just enable reset it will run forever as it will reset for every item that comes in from the loop branch. This brings the new question… How do I reset it for the second run of items? The example workflow that @ihortom gave us is below, In this workflow we w…

A summary, “Reset” option in the 2nd loop(inner), and reference to the last node name that runned from outer loop.

Eg : expression in Reset option

{{ $prevNode.name == ‘Group programs by days’ }}

Assuming that was the last runned node in the 1st loop.

Cheers!

[solomon]

Very interesting! Yes, that seems to be the case.

Try this solution, @TrinhNhatHuy

[TrinhNhatHuy]

@Parintele_Damaskin and @solomon thank you so much, i have successfully solved my problem.