Did you as me get surprised when all Azure Powershell integrations created for my Automation Platform started lightning up error messages about authentication or unverified certificates?
We had the poor timing of renewing our global domain certificate the same day the error messages started surfacing. After several attempts to solve the issue with a certificate in focus the time had come to bring out the big hammer, Google...
Some suggestions were to renew the certificate or remove and reinstall the certificate on the Azure AD server. Others were more on point.
The solution that solved the problem for me was the following, there might be others I haven't encountered so feel free to comment on your solution.
1. The AzureAD module got resolved by simply updating the module to the latest version (with PSGallery)
Install-Module AzureAD -Force
2. The MSOL (Microsoft online) module was resolved by updating the module as well as adding the SSL/TLS protocol (with PSGallery)
Install-Module MSOnline -Force
2.1 Add the following to the top part of your script to run the session with a secure protocol
[Net.ServicePointManager]::SecurityProtocol = [Net.SecurityProtocolType]::Tls12
More information regarding, why this error occurred can be read on Microsoft Azures website
How to connect to AzureAD
Thanks for reading and good luck!