My wireless keyboard and mouse stopped working. I tried to re-pair the two, and it is coming up with an message saying “The pairing attempt was unsuccessful. This configuration of Mac OS X and Bluetooth software could be invalid or unsupported”.
I called Apple. They asked if I had the current software updates which I did. Their solution was to return the devices to the Apple Store an hour+ away from where I live.
Here’s the solution that worked for me, posted by Alon in the Apple forums:
Reset the SMC.