What does "Failed to open swapfile" mean and is it a problem? A couple of times a day my fans start spinning, ready for take off. The activity manager shows that Mail is eating up my CPU, 250% and more.

The console shows the following lines:

13-09-16 10:46:46,000 kernel[0]: Failed to open swap file 2
13-09-16 10:46:46,000 kernel[0]: vm_swap_create_file failed @ 42649 secs


And continues to do so for quite a long time. Is this a problem and if so how can I fix this?

OS Version: El Capitan 10.11.6

Hardware: MacBook Pro (Retina, 15-inch, Mid 2014), 16 GB RAM, 256 GB SSD.
This could mean a number of things and yes, I would be concerned about it. First things first, ensure you have a working backup.

My next suggestion would be to reset both the PRAM/NVRAM and the SMC to see if this changes your computer's behaviour.

Reset your PRAM/NVRAM

Older Macs had what's called Parameter RAM (PRAM), newer Macs use Non-Volatile Random-Access Memory (NVRAM). Here’s how to reset your PRAM/NVRAM:


Shut down your machine. Yes, a full shut down, not just logging out.
Press the power button and then press the command-option-p-r keys. You have to make sure you press these keys before the gray screen appears or it won’t work.
Hold those keys down until your Mac reboots again and you here the startup chime.
Let go of the keys and let your Mac reboot normally.


Note: When you log back in you may need to readjust some of your system preferences (e.g. mouse speed, time and date/timezone, etc).

Reset the SMC

Your computer's System Management Controller (SMC) can also be reset. The instructions for resetting your SMC depend on three things:


Does your device run from a built-in battery? 
Does your device run from a removable battery? 
Does your device just run off power from the wall?


Now, since I don't know what computer you're using, I will provide the process for resetting the SMC in all three scenarios. Just use the one that is appropriate for your machine.

For MacBook Pros, MacBook Airs, and MacBooks where you can’t remove the battery on your own (i.e. it's a built-in battery), here’s what you do:


Shut down your computer
Keep the MagSafe adapter (power cable) plugged in.
Press at the same time shift-option-control (on the left side of the keyboard) and the power button
Let go
Turn your computer back on with the power button.


For MacBook Pros, MacBooks etc that you can remove the battery from, here’s what you do:


Shut down your computer
Disconnect the MagSafe plug (power cable) from the computer
Remove the battery
Press the power button for 5 seconds and release
Put the battery back in
Reconnect the MagSafe cord (or power cable)
Turn your computer back on with the power button


For iMacs, Mac Pros, Mac Minis, etc that only run from a power point in the wall


Shut down your computer
Unplug it from the power
Press and hold the power button for 5 seconds
Plug it back in and turn it on.


Hope this helps. Please report back and let us know.