Merge not returning data in test mode

[geggeri]

Bug Description

A merge node does not return any items when testing a node after the merge. The merge uses the append option, but one of the appended branches never reaches the merge. When running the full workflow it works as expected, but when testing from within a node (after the merge), the merge does not return any items

To Reproduce

Create a workflow with 3 branches. Let the first branch end without result and let the two other branches return something.

Each of the branches should be connected to a merge node using the append option.

Expected behavior

To work as it does on a full run.

Operating System

n8n cloud

n8n Version

1.70.4

Node.js Version

n8n Cloud

Database

SQLite (default)

Execution mode

main (default)

[Joffcom]

Hey @geggeri,

We have created an internal ticket to look into this which we will be tracking as "N8N-8037"

[MarcL]

Hi @geggeri,

I've been trying to recreate this but I can't seem to get it to happen.
Can you clarify your reproduction of the issue please?

Here's what I've tried:

Branches 2 and 3 set some data but branch 1 doesn't.

In the NOOP node I get the following:

Am I missing something in my workflow? Thanks!

[geggeri]

Hej Marc I cannot recreate it anymore. When I reported it I was able to recreate it within my workflow, but I just tried again and now I cant. Might have just been a UI / browser glitch. Sorry for the inconvenience Have a mice day Mads tirs. 7. jan. 2025, 13.15 skrev Marc Littlemore ***@***.***>:

…

Hi @geggeri <https://github.com/geggeri>, I've been trying to recreate this but I can't seem to get it to happen. Can you clarify your reproduction of the issue please? Here's what I've tried: CleanShot.2025-01-07.at.12.13.23.png (view on web) <https://github.com/user-attachments/assets/57c9ccdf-042c-435c-8d4a-1bc02959be6e> Branches 2 and 3 set some data but branch 1 doesn't. In the NOOP node I get the following: CleanShot.2025-01-07.at.12.14.21.png (view on web) <https://github.com/user-attachments/assets/8abeb280-77f3-428b-af5d-2c17fdbd26d4> Am I missing something in my workflow? Thanks! — Reply to this email directly, view it on GitHub <#12436 (comment)>, or unsubscribe <https://github.com/notifications/unsubscribe-auth/AATXWD2TRPXWIPNRV7OPDHD2JPAP7AVCNFSM6AAAAABUQSZGPCVHI2DSMVQWIX3LMV43OSLTON2WKQ3PNVWWK3TUHMZDKNZVGEZTONRUG4> . You are receiving this because you were mentioned.Message ID: ***@***.***>

[luizv]

I'm guessing I got a related problem. It was happening on 1.72.x and still on after I just updated on 1.73. Tested on Chrome and Safari. Running Cloud. This problem occurs everytime i have to merge two streams, not necessarily with merge node.

Recording:

• https://github.com/user-attachments/assets/55d3dae8-b144-4553-887d-82bd5e4f5397

As you can see on the recording, it bugs when there is a merge earlier in the flow.

And the flow I'm breaking in the recording is a dead branch in this execution:

Other tests:

• If I just ran through test workflow button, it runs everything, and shows me the inputs on nodes after the merge. Still nothing shows after I hit "test steps" or "run previous nodes".
• Beside noOp node, I also tried Merge with Append, and got the same result.

[MarcL]

@geggeri - No problem. Thanks for the update. Let us know if you hit any more issues.

@luizv - Thanks for the extra info. Let me try to recreate it locally.

[MarcL]

@luizv - Have you got a simple reproduction (without using external APIs if possible)? Can you post the JSON if you have?
I've tried a simple workflow with an If and Merge node and I can't recreate it.