Ubuntu 14.04 won't boot unless connected to an HDMI screen

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  • Updated 3 years ago
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  • (Edited)
Hi all - need a little help here.

I've setup a Linux box with Ubuntu 14.04 LTS and all is running well but I have one problem I cannot find a solution for.

If I turn the monitor off the hardware won't reboot. The monitor uses a HDMI input and it seems to be an issue with Ubuntu. As the monitors will be switched off at end of day and there is an automatic reboot set for the middle of the night it will prevent the system restarting.

Has anyone encountered this and have a solution?

regards,
Jim Coyle
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Jim Coyle, Champion

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Posted 3 years ago

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Robb, Official Rep

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Jim,

I can't say that I have run into this on my Ubuntu boxes that are connected via HDMI. I turn the monitor off, on, and everything works as expected.

Just to confirm you are saying that when the screen is off, the nightly reboot does not occur? Or it reboots, and just does not come back online?
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Jim Coyle, Champion

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Hi Robb,

Many thanks for your prompt response.

If the monitor is switched off the hardware won't reboot. I leave the monitor on and all starts as normal. This only seems to happen with HDMI and this doesn't occur when using VGA input as the system reboots as expected.

I am testing this using the scheduled reboot function which behaves as expected but only restarts the machine if the monitor is left on when using the HDMI input.  It isn't that the display is suspended or anything like that - I have teamviewer installed and cannot connect using this - it appears the machine has failed to reboot.

I seen users on other forums having similar issues with an HDMI monitor powered off when trying to reboot but none of the 'solutions' given have proved effective. Most seem to point to GRUB settings and one to xorg.conf but no success so far.

regards,
Jim Coyle
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Alan Clayton, Official Rep

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Hi Jim, I think what you are seeing is due to Ubuntu getting stuck on boot up when a monitor is not detected. As you've pointed out, users on other forums are reporting the same.

Do you still have this problem if you leave the HDMI connected and the display is in standby mode versus having power turned off?

Conversation here may be helpful, http://askubuntu.com/questions/611991/ubuntu-14-04-with-unrecognized-monitor-or-without-monitor-boot...

Let us know how you make out.

Thanks
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Jim Coyle, Champion

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Many thanks Alan and that link was very helpful. I still haven't got this sorted but at least I have a clearer idea of what the issue is.

I think it stems from there being no EDID coming from the monitor when it is switched off during reboot.

When I get the solution I will post it here.

regards,
Jim Coyle