Get help using our products.
First, please make sure you are using iDefrag 5.1.3 (for machines running OS X 10.11 or earlier), or iDefrag 5.1.7 or later (for machines running macOS Sierra or later). In particular, version 5.1.5 and 5.1.6 have a problem with the code signature on one of our kernel extensions, which upsets macOS Sierra. Note that 5.1.7 will not necessarily cure the problem completely — it may still take a long time to shut down on the first occasion — but this will only happen once.
On the first restart after installing iDefrag, some machines take a long time to shut down and will sit with a black screen for many minutes (we’ve seen them take as long as an hour here).
It appears that what’s going on is that the automatic kernel cache rebuild is taking a very long time for some reason. If this happens, some users (us included) get fed up and force the machine to shut down, but that can result in either a damaged kernel cache or in the cache not including the new KEXTs that are required for iDefrag’s reboot-and-defragment to work. Very occasionally, machines with broken kernel caches won’t even boot.
If you are in this situation do not panic. Simply
Enter the command
kextcache -i "/Volumes/Macintosh HD"
If you have renamed your hard disk, you may need to adjust the above command accordingly.
Wait for it to complete. It should take about 10-20 seconds.
We have reported this behaviour to Apple (rdar://29732811), as it’s clearly a bug in the macOS that it should take so long if a rebuild is happening during shutdown when rebuilding normally takes seconds.
Posted by alastair at 2016-Dec-19 13:12:05 UTC. Last updated 2017-Jan-15 18:01:55 UTC.