Windows 10 Build 17763 is the Official RTM Build of Windows 10 October 2018 Update.
The original release of this update from 2018-10-02 has a bug that deletes every file in the My Documents, My Music, My Pictures, and My Videos directories when updating from older versions of Windows 10. Back up all data before updating or disable the "Delete user profiles older than a specified number of days on system restart" group policy prior to installation if the updating SKU is Pro.
This update revision was pulled from Windows Update on 2018-10-06.
Microsoft fixed the data loss bug and released a bugfixed version for Insiders on 9 October 2018. It was re-released on Windows Update on 2018-11-13.
The re-release of the update included another bug in which Windows 10 Pro licenses would show as not being activated. If a user used the Windows Activation troubleshooter to fix it, it would say that the device had found a digital license for Windows 10 Home and that they had to install it to activate the device. It was made available for advanced users on 2018-12-11.