This answer record serves as the Vivado 2018.2 tool update 1 (2018.2.1) Release Notes, and contains links to information about what is included in the update.
The Vivado 2018.2 tool update 1 (2018.2.1) addresses the following issues:
Vivado 2018.2 Update 1 provides:
Zynq UltraScale+ MPSoC (-3) Devices
For customers using these devices, Xilinx recommends installing Vivado 2018.2.1.
For other devices, please continue to use Vivado 2018.2.
Downloading and installing the Vivado 2018.2 update (2018.2.1)
Known Issues specific to Vivado 2018.2 update 1 (2018.2.1)