Do not use custom Windows Theme and Icon Pack 1803 for the latest 1809 version update
Wait for the author to send you the update/make it available on their websites.
I will update the theme links on my website as well over time.
You will also have to update to the latest UxthemePatcher (version 3.5.0, click for download).
If you happen to have already installed the update with a theme activated, you will not be able to log into your session, Windows will bring you back to your lockscreen, because of small incompatibilities with the latest interface. All you have to do is force the restart of your computer approx. 3 times with your shut-down button, then Windows will load a blue screen with a few options available, where you can roll-back to the latest update.