Basic LLM Chain doesn't handle On Error correctly

[dkindlund]

Bug Description

I have a workflow using a Basic LLM Chain with the On Error param set to Continue (using error output) like this:

When I feed in an input to the LLM that flags on their content filtering policy, this sort of error gets thrown by the node:

NodeOperationError: 400 AzureException - Error code: 400 - {'error': {'message': "The response was filtered due to the prompt triggering Azure OpenAI's content management policy. Please modify your prompt and retry. To learn more about our content filtering policies please read our documentation: https://go.microsoft.com/fwlink/?linkid=2198766", 'type': None, 'param': 'prompt', 'code': 'content_filter', 'status': 400, 'innererror': {'code': 'ResponsibleAIPolicyViolation', 'content_filter_result': {'hate': {'filtered': False, 'severity': 'safe'}, 'self_harm': {'filtered': False, 'severity': 'safe'}, 'sexual': {'filtered': True, 'severity': 'medium'}, 'violence': {'filtered': False, 'severity': 'safe'}}}}}
    at ChatOpenAI.callMethodAsync (/usr/local/lib/node_modules/n8n/node_modules/@n8n/n8n-nodes-langchain/dist/utils/logWrapper.js:34:23)
    at processTicksAndRejections (node:internal/process/task_queues:95:5)
    at Proxy.connectionType (/usr/local/lib/node_modules/n8n/node_modules/@n8n/n8n-nodes-langchain/dist/utils/logWrapper.js:156:47)
    at async Promise.allSettled (index 0)
    at Proxy._generateUncached (/usr/local/lib/node_modules/n8n/node_modules/@n8n/n8n-nodes-langchain/node_modules/langchain/node_modules/@langchain/core/dist/language_models/chat_models.cjs:114:25)
    at LLMChain._call (/usr/local/lib/node_modules/n8n/node_modules/@n8n/n8n-nodes-langchain/node_modules/langchain/dist/chains/llm_chain.cjs:157:37)
    at LLMChain.call (/usr/local/lib/node_modules/n8n/node_modules/@n8n/n8n-nodes-langchain/node_modules/langchain/dist/chains/base.cjs:120:28)
    at createSimpleLLMChain (/usr/local/lib/node_modules/n8n/node_modules/@n8n/n8n-nodes-langchain/dist/nodes/chains/ChainLLM/ChainLlm.node.js:84:23)
    at getChain (/usr/local/lib/node_modules/n8n/node_modules/@n8n/n8n-nodes-langchain/dist/nodes/chains/ChainLLM/ChainLlm.node.js:93:16)
    at Object.execute (/usr/local/lib/node_modules/n8n/node_modules/@n8n/n8n-nodes-langchain/dist/nodes/chains/ChainLLM/ChainLlm.node.js:407:31)

But what's really weird is that the SUCCESS path of the node is executed instead of the ERROR path:

And when I try to see the data returned to the Airtable nodes, it's completely EMPTY:

To Reproduce

1. Create a workflow using the Basic LLM Chain
2. Configure the node to use On Error set to Continue (using error output)
3. Feed in a prompt that triggers OpenAI's content filtering policy
4. Watch as error gets caught but sent down the SUCCESS path instead of ERROR path
5. Also, no data from the error is provided to subsequent nodes downstream from the error, which is also a bug

Expected behavior

I'd expect this configuration to catch the error, evaluate the ERROR path, and provide details of the error to the downstream node.

Operating System

Google Cloud Run

n8n Version

1.31.2

Node.js Version

18.10

Database

PostgreSQL

Execution mode

main (default)

[Joffcom]

Thanks for the report, I have created NODE-1254 as the internal dev ticket to get this added.

[janober]

Fix got released with n8n@1.37.0