I am trying to subscribe to pending transactions on the Ethereum blockchain using this tutorial from Infura: https://docs.infura.io/tutorials/ethereum/subscribe-to-pending-transactions

When I try to execute the .py file in Terminal it reads:

''' websockets.exceptions.InvalidStatusCode: server rejected WebSocket connection: HTTP 401 '''

I am very unfamiliar with Python and Infura websockets. What is the problem with my code and how can I correct it?

  • Hi, make sure to add the WebSocket endpoint in the variable infura_ws_url. It worked as expected for me! Aug 3 at 23:22

1 Answer 1


GM, Developer Relations Lead at Chainstack here.

Assuming you're using the full code snippet provided in that article, this error stems from an attempt to open a WebSocket connection on an invalid endpoint- this most likely means that the URL you're using in async with connect(URL) as ws: is not a valid WebSocket endpoint~ which could be the result of not using the right endpoint authentication (the string that goes into <YOUR_API_KEY>)

As a side note, the code provided in this article works for me with a Chainstack Elastic Node.

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