Failed to parse agent steps

Questions
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1

Describe the problem/error/question

Since I installed the latest version “2.25.6”, whenever I use a “Basic LLM Chain” node with a structured output parser, I get an error “Failed to parse agent steps”.

Basically, it’s not going through the structured output parser node.

I tested it with the “AI Agent” node and it works fine.

Information on your n8n setup

  • n8n version: 2.25.6
  • Database (default: SQLite): Postgres
  • n8n EXECUTIONS_PROCESS setting (default: own, main):
  • Running n8n via (Docker, npm, n8n cloud, desktop app): Docker
  • Operating system: Ubuntu
2

Hi, @Pedro_de_Pedro

Based on what you’re saying, it seems like a specific issue with how the Basic LLM Chain node handles agent steps when used together with Structured Output Parser in version 2.25.6. In many cases the workflow doesn’t even reach the Structured Output Parser node and returns Failed to parse agent steps, whereas the same use case works correctly if you switch to the AI Agent node.

For now, using AI Agent is a good temporary solution, but it would be good if the team could confirm whether this is a known bug in Basic LLM Chain in 2.25.6 or if there’s any recommended configuration to avoid this error.

3

I ran into something similar after upgrading and it’s worth checking a few things before assuming it’s a full bug.

First, delete the connection between the structured output parser and the Basic LLM Chain node completely, then reconnect it fresh. After version upgrades the sub-node connections sometimes break silently and rewiring them fixes it without changing anything else.

Second, double check your structured output parser schema. Sometimes a small schema mismatch that previous versions were forgiving about becomes a hard failure in newer versions.

If neither of those work, the quickest workaround right now is switching to the AI Agent node since you’ve confirmed it handles structured output fine on this version. For most use cases it does the same job.

Also check the n8n GitHub and search for Basic LLM Chain structured output 2.25.6 — if others hit the same thing after upgrading there may already be an open issue or a fix coming in a patch.

The error message itself is interesting because “Failed to parse agent steps” normally belongs to agent flows, not a Basic LLM Chain. That tells me something in 2.25.6 changed how that node processes the parser output internally. Worth raising a GitHub issue if nothing comes up in your search.