Trello Node – “Invalid objectId” when adding labels via expression

[matsyui]

I’m trying to add labels to a Trello card using the Trello node in n8n (self-hosted v1.118.2). The workflow receives type and category from a webhook, and I want to map these to Trello label IDs dynamically.

Problem:

• When I return only one label ID, it works fine.

• When I try to return two or more labels (comma-separated), I get:

Things I’ve tried:

• Returning an array of IDs instead of a comma-separated string.

• Ensuring no undefined values are pushed.

• Making label matching case-insensitive.

I’m sending exactly one or two labels depending on the webhook, e.g., "bug" + "ui".

Has anyone successfully mapped multiple webhook values to Trello labels dynamically in n8n? Am I missing something about how the Trello node expects multiple label IDs?

[mohamed3nan]

Hello again @matsyui

I know this might look a bit strange, but I think there’s a hidden whitespace in your expression here:

[matsyui]

HOYLCRAP HAHAHAHA that invisible white space ruin it

[mohamed3nan]

yea, it happens to me a lot sometimes it can take hours to figure it out.

[Parintele_Damaskin]

Me 1h hour after trying to add and remove colons and semicolon… and it was the blank space.

Just love your eagle eyes !