iOS 9 Extensions installation issue in ConfigMgr with Intune (Hybrid scenario)

Last month Microsoft released the iOS 9 Intune extension for ConfigMgr. At a customer with Hybrid scenario (ConfigMgr with Intune) the following happens when opening the ConfigMgr console. A prompt is displayed that a new extension is available, with the choice to install it right away, or open the console in read-only mode. When select -install- an error message is displayed, and you can start all over again. Let's have a look at this.
 

The first message displayed is "Extensions for Microsoft Intune have been enabled or disabled for this site. To update this console with the changes, click Yes. To continue without updating the console, click No. The console will be restarted in read-only mode."
 

When select Install the following message is displayed: "The feature task requires that you close the Configuration Manager console. Close all open Configuration Manager consoles and retry the operation".

Trick is no ConfigMgr consoles are open, nothing seems to happen and reopening the console would bring me back to the start again!

Solution for this is to start an elevated (admin) command prompt and navigate to C:\Program Files (x86)\Microsoft Configuration Manager\AdminConsole\bin. Run AdminUI.ExtensionInstaller.exe /Q from there. After that the console can be opened fine, and no popup is displayed anymore.

Maybe useful for future updates too :-)