• No error is thrown — the expression silently resolves to [undefined], which then breaks downstream branching logic (IF / Switch takes the wrong path). Error Demo.json
• error: all

TL;DR

The issue can be worked around by re-evaluating the expression after the Execute Workflow node or by using a different approach to access the parent node's data.

Guidance

• The problem seems to be related to the scope and timing of expression evaluation in n8n workflows, specifically when using the Execute Workflow node with a Merge node in the sub-workflow.
• To verify the issue, try logging the value of $('Set Value').item.json.Value at different points in the workflow to see when it becomes undefined.
• As a potential workaround, consider using a Set node to store the value of $('Set Value').item.json.Value in a workflow variable before the Execute Workflow node, and then reference the variable instead of the original expression.
• Another approach could be to restructure the workflow to avoid back-referencing parent nodes after the Execute Workflow node.

Example

No code snippet is provided as the issue is more related to the workflow structure and expression evaluation.

Notes

The root cause of the issue is not entirely clear, but it seems to be related to how n8n evaluates expressions and handles scope. The provided workaround may not be the only solution, and further investigation may be needed to find a more robust fix.

Recommendation

Apply workaround: The safest approach seems to be to use a Set node to store the value of $('Set Value').item.json.Value in a workflow variable before the Execute Workflow node, and then reference the variable instead of the original expression. This should help avoid the issue with back-referencing parent nodes.