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FirefoxCP web content prevents mac from sleep

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Firefox 56.0.2 macOS Sierra 10.12.6 on iMac 27-in Late 2013

Several instances of "FirefoxCP Web Content" process are preventing Mac from sleep. Restarting Firefox fixes the problem, but then it shows up again after a while. Has been going on for a couple of months.

Apple Support claims the Mac and macOS are fine.

Firefox 56.0.2 macOS Sierra 10.12.6 on iMac 27-in Late 2013 Several instances of "FirefoxCP Web Content" process are preventing Mac from sleep. Restarting Firefox fixes the problem, but then it shows up again after a while. Has been going on for a couple of months. Apple Support claims the Mac and macOS are fine.

Chosen solution

You can try to modify multi-process settings to see if this has effect.

  • set dom.ipc.processCount to 1 if it is currently set to a higher value (4)
  • disable multi-process windows in Firefox

You can disable multi-process windows in Firefox by setting these prefs to false on the about:config page.

  • browser.tabs.remote.autostart = false
  • browser.tabs.remote.autostart.2 = false

You can open the about:config page via the location/address bar. You can accept the warning and click "I accept the risk!" to continue.

Read this answer in context 👍 5

All Replies (3)

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Chosen Solution

You can try to modify multi-process settings to see if this has effect.

  • set dom.ipc.processCount to 1 if it is currently set to a higher value (4)
  • disable multi-process windows in Firefox

You can disable multi-process windows in Firefox by setting these prefs to false on the about:config page.

  • browser.tabs.remote.autostart = false
  • browser.tabs.remote.autostart.2 = false

You can open the about:config page via the location/address bar. You can accept the warning and click "I accept the risk!" to continue.

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Thanks!!! Seems OK now.

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Seems like there's advantages to having multi-process enabled so maybe it would be good to find the reason for why automatic sleep is sometimes prevented?