Some have experienced data loss of their entire documents folder and other items. Back up your items and do not apply the update until MS can fix this. If you downloaded the update but it did not install you can follow these steps to delay the installation for 35 days. You also want to check off Pause Updates.

https://pureinfotech.com/prevent-windows-10-installing-april-2018-update-1803/

Here are my sources:

https://www.forbes.com/sites/jasonevangelho/2018/10/05/avoid-windows-10-october-update-until-you-do-one-thing/#371745273e79

https://www.reddit.com/r/Windows10/comments/9levfu/microsoft_windows_10_october_2018_update_can/