How can I resolve the 'input values have 3 keys' error when using memory with the AI Agent node in n8n?

Below is an explanation of the error and some troubleshooting steps based on similar known issues with the AI Agent node:

What the Error Means

The error message

input values have 3 keys, you must specify an input key or pass only 1 key as input

indicates that the node is receiving an input object containing multiple keys (in this case, three), while it expects either:

• A single key containing the prompt value, or
• A specific input key to be defined so it knows which field to use.

This situation can often occur when the AI Agent node is combined with memory nodes. For instance, if the node is set to automatically take input from the previous node, the additional keys (from chat history or other memory information) may end up bundled together, causing a conflict.

Suggested Solutions

Here are some troubleshooting steps you can follow:

1. Specify the Input Key Explicitly
   In your AI Agent node configuration, change the Prompt setting from "Take from previous node automatically" to "Define below" and then reference the correct input key. This tells the node exactly which piece of the incoming data to use.

2. Reformat the Incoming Data
   If you need to keep the automatic behavior, consider adding a Function or Set node before the AI Agent node to reformat the input data. Make sure that only the intended key (or field) is passed along. For example, if your input looks like this:

   JSONCopied
   {
     "chatHistory": "...",
     "input": "User question",
     "agent_scratchpad": "Additional context"
   }

   you might want to extract only the "input" field into a new object:

   JAVASCRIPTCopied
   // Example using a Function node:
   return [{ input: $json.input }];

3. Review Memory Node Configuration
   Since you are using memory with the AI agent, double-check that your memory node (e.g., Window Buffer Memory or any of the memory sub-nodes) is not unintentionally injecting extra keys into the input. Adjust its configuration if needed so that only the expected prompt is passed into the agent.

Additional Context

This error is similar to other input-related issues documented in the AI Agent node troubleshooting guides. For example, when the node receives a null value instead of a string, a different error is shown; the solution there is also to verify and clean up the incoming data. This key-related mismatch follows a similar root cause—ensuring that the input adheres strictly to what the node expects.

By explicitly defining the input key or cleaning your incoming data payload, the AI Agent node should be able to process the input without encountering the “too many keys” error.

If you continue to experience issues, ensure all related nodes (for both AI Agent and memory) are updated to their latest versions in your workflow.