The Console application in OS X contains a lot of system logs, and, lately, I have been noticing a lot of a particular error message.
The following error message was thrown 24 times over a 19 second period:
kernel: [SendRawHCICommand] ### ERROR: EnqueueRequestForController failed (err=e00002d7)
I had no idea what was going on or why this message was being thrown so often. To make matters more confusing, there wasn't anything going wrong with my computer. Typically, this number of error messages means something is going wrong.
A Google search returns few results, but a Reddit thread reveals some useful information.
In the comments of the aforementioned Reddit thread, a Reddit user states that "HCI probably stands for Host Controller Interface and could be either Bluetooth or USB".
Another Reddit user, who has the same issue, believes the error messages occur when you have a Bluetooth device connected, such as an iPhone, but you have Bluetooth turned off on the computer. When that Reddit user turned on Bluetooth on their computer, the error messages went away.
Sure enough, I had the same result. The moment I turned Bluetooth on, the error messages stopped.
However, I don't have my iPhone explicitly paired with my computer. I don't have any Bluetooth devices explicitly paired with my computer. My best guess is that this has something to do with the Instant Hotspot feature, or some other Continuity feature that requires Bluetooth.
In any case, it probably isn't something to be alarmed about.