Since Microsoft decided to introduce Windows as a Service concept for Windows 10 and later, it has become difficult for users to cope with the amount of updates Microsoft releases each month.
Although Microsoft has fixed the second Tuesday of every month for releasing updates, the updates can come at any day apart from the scheduled time. Users are facing one problem recently. They get the following error message when they try to install a new cumulative update.
Error. Failure to install SSU before LCU. Turn your computer off and back on again
To understand this error, we will need to know what is SSU and LCU.
SSU (Servicing Stack Update): This is the component of Operating System which is responsible for updating the Operating System. Windows Update services run under this component. It also contains Component-based Servicing (CBS) which includes other Operating System updating and configuration components like DISM, SFC, changing Windows features or roles, repairing components etc.
SSU is a small component. Microsoft does not update it very often. But when a new update is released, it is important to install the SSU update before installing any other OS related update.
LCU (Latest Cumulative Update): LCU is the last cumulative update released by Microsoft. Microsoft normally released one or two cumulative updates for each version of Windows 10 every month.
If you try to install LCU before updating the latest SSU, it will give the above mentioned error.
The SSU is downloaded and installed separately and does not come with the cumulative update. It is weird that Windows can’t update its component which is responsible for installing other Windows updates.
Solution to failure to install SSU before LCU
If you are downloading and installing the cumulative update separately, you should restart your computer and then run Windows Update. It should detect and install the latest SSU for you. After the servicing stack update is installed, you will be able to run and install the latest cumulative update.
Although you can download SSU from Microsoft Update catalog and install it separately, Microsoft does not publish a list of latest versions of servicing stack updates. If you know the KB article then it will become easy for you to download and install. Otherwise, you can use Windows Update to automatically detect and update the component.
For your information, the latest SSU for Windows 10 Version 1803 is KB4456655. You may download it from the following direct download links: