Oculus Rift headsets the world over have reportedly all stopped working.
Overnight, many Rift users reported on Reddit and other forums that the Oculus client was no longer launching, and that they were getting error messages such as "Can't Reach Oculus Runtime Service" and "Failed to initialise with Oculus: Signature Invalid".
"We are aware of and actively investigating an issue impacting ability to access Rift software," said Oculus in a statement.
"Our teams apologise for any inconvenience this may be causing you and appreciate your patience while we work on a resolution. We'll share more updates here as we have them. Thanks."
That left users in the dark, but some discovered that an expired security certificate within a file called OculusAppFramework.dll was probably responsible for the errors.
It appears to be possible to bypass the issue by disabling Windows' "Automatically set System date and time" option, then manually setting the date back a few days to when the certificate is still valid. Obviously, this can cause problems with other PC services like automatic updates, but it is working for some.