In case you're receiving the error "Can't Reach Oculus Runtime Service," when you try to launch Oculus Rift on your PC, you'll need to manually update your Oculus software before you can use your Rift.
To patch your Oculus software, you'll need to download 'OculusPatchMarch2018.exe' at https://www.oculus.com/rift-patch/. Run the executable, and select "Repair". When the update is finished, launch the Oculus desktop app to continue the update process. Once the update is complete, you'll be able to use your Rift.
A step-by-step walkthrough is available here: https://support.oculus.com/217157135500529/
A manual update is only necessary if you're unable to start the Oculus desktop app - if you aren't seeing an error, the system will update itself to the new version automatically.
Oculus is providing a $15 Oculus Store credit (or currency equivalent) to people impacted by this issue. If you used Rift on or after February 1st, 2018 this credit will be added to your account automatically within the next 7 days. See this page for info about Oculus Store credits.