Error when executing sub-workflow

[Henri_Chabert]

Hello everyone !

Describe the problem/error/question

I had a regression since I updated n8n to the last version. The following error appears on one of my workflow:
In node ‘Send Numeric Certificate 2’, output item 0 of points to a branch that doesn’t exist.

I don’t understand why this message appears while it was working perfectly before I migrate (Went from 1.32 to 1.39 I think).

If it can help to investigate, I also have a strange behaviour running a sub-workflow prior to the step generating an error. Although the output of the sub-worflow shows some data, I can’t find this data in the output of the next node (see screeshots)

What is the error message (if any)?

In node ‘Send Numeric Certificate 2’, output item 0 of points to a branch that doesn’t exist.

Please share your workflow

Share the output returned by the last node

The last node generates an error.

Information on your n8n setup

• **n8n version:1.39.1
• **Database (default: SQLite):SQLite
• **n8n EXECUTIONS_PROCESS setting (default: own, main):default
• **Running n8n via (Docker, npm, n8n cloud, desktop app):Docker
• **Operating system:Ubuntu 22

[Henri_Chabert]

Hello !
So I ran some investigations, and it seems the problem comes from the fact that the sub-workflow ends with a Merge Node. I fixed it by happening a “Do Nothing” node after the Merge one.
Is this an expected behaviour ?

[barn4k]

hello @Henri_Chabert

Maybe, but better to set the expression as {{ $('Input').last().json.certificate_url }}