I put my computer (Windows 8.1 Pro) to sleep every evening.

For a couple days now, I find it awake in the morning. A quick check in Event Viewer shows that it actually woke up and (apparently) put itself back to sleep again many times during the night, about every half hour.

Event Viewer this morning

This is new and was not happening three days ago. I have already taken great care to make sure my computer doesn't wake up for no good reason:

  1. Windows Update is setup to download updates but to let me choose whether or when to install them:

Windows Update Settings

  1. Wake timers are disabled for the power plan I'm using:

Power Options

  1. I prevented all devices from waking the computer up:

    C:\>powercfg -devicequery wake_armed
  2. As far as I can tell, no active Scheduled Task is allowed to wake the computer up to run.

  3. A quick check with Windows Defender (with up-to-date definitions) does not detect any malware (not that Windows Defender is really good at finding them...)

A few more (possibly unrelated) details:

  • My computer has been up for 10 days now. This isn't unusual, I often reach uptimes of 30 days or more.

  • I often have (paused) YouTube videos open in browser tabs when I put the computer to sleep. Again this hasn't caused problems so far.

Any idea what could be causing this, and how to make sure my computer does not wake up?

  • Observed in Windows 7 as well, guess it's due to some patch Microsoft installed that breaks hibernation mode. No surprise, they break stuff many times. :/ – Shadow Wizard Aug 17 '15 at 7:15
  • That's very possible. Interestingly, sleep mode has been working again for a few days. – François Beaune Aug 17 '15 at 11:56
  • Not for me. Hopefully this will either resolve itself (new patch?) or we'll get answer here. :) – Shadow Wizard Aug 17 '15 at 12:00

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