Missing Authentication Token Exception for AWS custom operation

Describe the problem/error/question

When attempting to use an AWS API operation that is not supported by the built-in AWS workflow nodes, I follow the advice to use a custom operation:

I define the custom operation using a HTTP Request node, choosing the pre-defined AWS credentials:


However, the request fails with:

400 - "{\"__type\":\"MissingAuthenticationTokenException\",\"message\":\"Missing Authentication Token\"}"

I also notice that the Authorization header is not being sent with the request.

This seems to be the same problem as two users were describing in…

…but that thread doesn’t appear to result in a conclusion on the authorization issue.

What is the error message (if any)?

400 - "{\"__type\":\"MissingAuthenticationTokenException\",\"message\":\"Missing Authentication Token\"}"

Please share your workflow

(Select the nodes on your canvas and use the keyboard shortcuts CMD+C/CTRL+C and CMD+V/CTRL+V to copy and paste the workflow.)

Share the output returned by the last node

Information on your n8n setup

  • n8n version: 1.72.1 (Cloud)
  • Database (default: SQLite):
  • n8n EXECUTIONS_PROCESS setting (default: own, main):
  • Running n8n via cloud:
  • Operating system: default

It looks like your topic is missing some important information. Could you provide the following if applicable.

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

I’m facing the same issue.
For me, I need to do an AWS Textract type that isn’t supported in the n8n node, so followed the docs…


This IS NOT WORKING.

There are a few other threads describing the exact same issue.

I’d be happy with any sort of workaround. I was happily using Textract until I now need to do Forms ocr extraction.

Any help (better instructions, a workaround, official fix) is greatly appreciated.

Small follow-up. I am able to get the same HTTP request to work in Postman using it’s AWS Auth Type.

@GollyJer - my hunch here is that this simply doesn’t work. I tried everything I could, but couldn’t get it to work.

My only option was to invoke lambda functions from my n8n workflow (where the authentication can be configured as I need) and then interact with the relevant service e.g. Textract from within the function.

Hope you’re able to move forward!

Yeah, I gave up on it.

Turns out it pushed me to find a better solution.
I’m now using Gemini 2.0 Flash for an initial scan & Gemini 2.0 Pro + OCR.space for a validation scan and getting much better results than we ever achieved previously.

1 Like

@GollyJer wonder how you managed to get Gemini 2.0 Flash & Gemini Pro + OCR work, would you mind sharing?

Makes me feel better to see someone else facing the same issue. I’ve spent a lot of time trying to get Textract to work in an http node with no luck. I’m also using OCR space, but it has relatively low success/accuracy rate for my use case so I will try Gemini 2.0 Flash. Thanks!

Hi @Jorge_Castellote. My use case is pretty specific but here’s a screenshot of the flow. I think most people can get away with just the first pass to the LLM Scan - Images Only.

The passes through OCR.space and the second LLM, for us, were because Gemini 2.0 Flash doesn’t do the best with small blurry text and OCR.space could sometimes pick up the words that Gemini couldn’t. From the red box and after is probably not necessary for most use cases.

Would just like to add, I’m having the same problems as well with the HTTP node and using my AWS Credentials. Same as OP, I’m also trying to use Transcribe.

I know my credentials are correct as when I use any other AWS node (such as S3, which I have earlier in my flow) it works correctly.

Having the same issue

Hey all I found creating a Lambda function as a proxy then using the Lambda node to call it works. the AWS Signature Version 4 authentication does not work in the http request node.