Web3.py – Fixing AttributeError: ‘Web3’ Object Has No Attribute ‘middleware_stack’

You're trying to use a v4 feature. Chances are good that you have v3 installed. To install the latest v4 version, use:

pip3 install --upgrade web3

For web3.py==5.x.x

GethShh

The web3.geth.shh object exposes methods to interact with the RPC APIs under the shh_ namespace.

For web3.py==4.x.x

=> We have to add the following line of code in order to fix the error for the web3.py:

from web3.shh import Shh
Shh.attach(web3, "shh")

=> We also have to add the following line for web3.js. Than use shh.

var Shh = require('web3-shh');   
var shh = new Shh(Shh.givenProvider || 'http://localhost:8545'); 

Please see following solution for web3.py:

from web3 import Web3, HTTPProvider
web3 = Web3(HTTPProvider('http://localhost:8545'))

from web3.shh import Shh  # Added line
Shh.attach(web3, "shh")   # Added line

# Now we call web3.shh as we would like:

# Example
print(web3.shh.version) #5.0
kId = web3.shh.newKeyPair();    
print(kId)
print(web3.shh.getPrivateKey(kId))
...

Please see following solution for web3.js:

$ npm install web3-shh

Example code:

web3 = new Web3(new Web3.providers.HttpProvider("http://localhost:8545"));    
if(!web3.isConnected()){console.log("notconnected"); process.exit();}

var Shh = require('web3-shh');
// "Shh.providers.givenProvider" will be set if in an Ethereum supported browser.
var shh = new Shh(Shh.givenProvider || 'http://localhost:8545');

var kId = shh.newSymKey().then(console.log); //returns a valid value.