HTTP Agent Node Error: 'Operation not Permitted' in n8n on Docker

Below is a checklist to help troubleshoot the error:

1. Validate Your Prompt/Content Field

If you’re using a node that expects a prompt or content string (for example, the AI Agent node), you can run into issues when the value is null. In particular:

• If you’re set to Define below and using an expression, ensure the expression is actually returning a non-null, valid string.
• If you’re set to Take from previous node automatically, verify that the incoming data isn’t sending a null value—if it is, adjust your workflow to remove these null values before they’re passed on.

An error message such as:

  Internal error: 400 Invalid value for 'content': expected a string, got null.

reminds you that the node did not receive the correct input.

2. Double-Check Node Configuration

• Confirm that every required field in the node is filled in with valid data.
• If your HTTP (or agent) node is configured to build a prompt or content based on previous data, check that the upstream node is returning the expected value.

3. Review Workflow Data

Examine the data that flows into this node:

• Use a Debug node or the n8n execution log to inspect the input data reaching your problematic node.
• Remove or replace any null values as needed.

4. Update n8n (if applicable)

Your version is 1.64.3. While not necessarily the root cause, consider checking the latest documentation or upgrading if you believe it might help resolve any bugs that have been fixed in later versions.

Following these steps should help resolve the error you’re seeing. If you still run into trouble, please share the detailed node configuration (excluding any sensitive data) and the structure of the incoming data so we can assist you further.