Hi Andrew,
Corrupted or incomplete installation can be one of the possible reason why an update may fail. The error message 0xC1900101 - 0x30018 The installation failed in the FIRST_BOOT phase with an error during SYSPREP operation may possibly occur due to incompatible driver or hardware. To assist you better, we'd like to know if you've made any recent changes prior to this issue.
Meanwhile, we suggest that you follow the steps in this article to troubleshoot Windows update issues. You can choose which version of Windows your experiencing the problem.
Keep us posted if you need additional help.
The article was very nice up to the point it indicated a complete wipe of my system...
There must be a way to know which device Windows 10 fall update is having problems with and then reload that device.
I went through the procedure with no solution... right up to the system wipe....
any other suggestions???