Can't import SharePoint online Powershell module

To work with SharePoint online, you need the SharePoint Online Management Shell PowerShell module. Once installed (on your Windows 10 machine), SharePoint Online PowerShell will be loaded automatically in the PowerShell console as well as ISE without importing the module manually.

You need to connect SPO like this:
Connect-SPOService -Url https://contoso-admin.sharepoint.com -Credential email address removed for privacy reasons

After -Credential type the SharePoint Online administrator email.

Andy_Bond, It took me a full day to come to this work around. Thanks for your question and @Glenn's response (which by the way, didn't work in my case)

Main Error:
Connect-SPOService : The 'Connect-SPOService' command was found in the module 'Microsoft.Online.SharePoint.PowerShell', but the module could not be loaded. For more
information, run 'Import-Module Microsoft.Online.SharePoint.PowerShell'.

Sub-Error:
Import-Module : Could not load type 'Microsoft.SharePoint.Client.CustomerRecoveryKeyMode' from assembly 'Microsoft.SharePoint.Client, Version=16.0.0.0, Culture=neutral,
PublicKeyToken=71e9bce111e9429c'.

Solution:
 If you get this error while trying to use Connect-SPOSite command in your script, then close the PowerShell Session completely
Uninstall module Microsoft.Online.ShareP¬oint.PowerShell and install it again, then import it again
If you have trouble importing (Error: Can’t import), then use Glenn’s solution and it shall work and says: “Successfully imported” (even with Client Component SDK installed but just those specific files are removed)

{

Glenn's solution:

(1) Navigate to C:\Windows\Microsoft.NET\assembly\GAC_MSIL
(2) Remove the Microsoft.SharePoint.* assemblies

}

After successfully importing, you must not put those removed files back in their place, you’ll get the same error (tried it)

Now, to avoid encountering the same error again while you run that script the next time,

keep these in mind:

1) PowerShell Session means when you freshly open PowerShell ISE window, session ends when you completely close PowerShell ISE Window
2) Whenever you open a new PowerShell Session, BEFORE running anything related to  loading CSOM assemblies & $ctx client context, ctx.execute query and all of that ClientComponent related stuff, just Run the ConnectSPO-Site Command once, and then do whatever you want with whatever scripts you have
 Enjoy! (and you’re Welcome😊)

Andy_Bond and anyone else interested.

I have done several days searching for a solution and believe I have come across a few causes and solutions.

The obvious one is multiple versions of the module installed. The obvious is to uninstall all versions and install the latest either using Install-Module or obtaining the MSI from Microsoft. Very annoying but it does ensure that you have a reasonably clean environment. Along with uninstalling all versions is to follow the instructions provided by Glenn Goffin unless, of course, you are doing this on a SharePoint server. Do not delete those directories from your SharePoint server!

Another interesting one surfaced where the error was being generated within the Exchange Management Shell (EMS) but didn't happen with the standard PowerShell window.
We onboard hundreds of accounts a day and part of the onboarding includes OneDrive test and request. The EMS, it turned out, this was our issue. As a result, I ended up writing the following function to replicate the EMS in a normal PowerShell window. Please read through...

if (!($exscripts -and $ExPath)) {
	$path = "HKLM:\Software\Microsoft\ExchangeServer"
	$keys = Get-ChildItem -Path $path -Recurse

	ForEach($Key in $Keys) {
		ForEach ($Value in (Get-ItemProperty -Path $key.PSPath -Name "MsiInstall*")){
			if ($Value.MsiInstallPath -match "Exchange" -and $Value.MsiInstallPath -match "bin") {
				$ExPath = $Value.MsiInstallPath
			}

		}
	}
	if (Test-Path $ExPath) {
		$ExPath = "$ExPath\RemoteExchange.ps1"
		. $ExPath
	}
	else {
		Write-Host "Exchange tools are not installed on this server or are installed in a different path" -ForegroundColor Yellow
		"Check the tools are installed and update the path in $($MyInvocation.MyCommand.Name) and search for '$ExPath'"
		Exit-Script
	}
}

$EXSession = Get-PSSession | Where-Object {$_.ComputerName -match "Partial_HostName"} ## We have an exchange cluster with incremental naming convention

if (!($EXSession)) {
	"Connecting to Exchange"
	Connect-ExchangeServer -Auto -AllowClobber
}

Obviously, this will only work if you have the Exchange tools installed on the host running the script.

The trick is to load the SharePoint Online modules first and then the EMS code above. So far, in the last 4 hours and the script running every 5 minutes, there has not been an error.

To note, we are running a hybrid Exchange environment so I am not sure if the issue is present when the Exchange Online tools are loaded before SharePoint Online as I moved SharePoint to be the first module loaded.

Manual removing CSOM assemblies from the GAC is not a good idea - especially if you have SP on-prem running on the same server. Problem is caused by several instances of SPO SDKs and may be solved this way:

1. Open Control Panel -> UnInstall Programs -> Search for SharePoint related setups.
2. Locate SharePoint Client Components -> Uninstall.
3. Locate SharePoint Online Management Shell -> Uninstall.
4. Ensure that anyone of the above setup is installed more than one time. If so, remove all the instances.
5. Now, open the Powershell console in administrative mode (Run as administrator).
6. Uninstall SPO Powershell module (If already exists) by running this command: Uninstall-Module -Name Microsoft.Online.SharePoint.PowerShell -AllVersions -Force
7. Finally, install the latest SPO Powershell module by running this command: Install-Module Microsoft.Online.SharePoint.PowerShell -Force