I have getting this error and it toughing this message,

Guzzle POST returning GuzzleHttp\Exception\ClientException Client error: `POST http://your.website. resulted in a’401 unauthorized’ response:

So I check out my .env file because client authentication in define here

then i find my error

It should be like this (in my case, your will be different)

How to check your URL is right or not

you have to copy and paste this URL to your web browser, if URL is working and shows your start page of your website, if it is not working then this is not your right URL.