The brightness bug seems to strike at random for me. Its infrequent but annoying. Sometimes just leaving the PC on but unattended is enough for it to reset to 50% (maybe after the screen timeout period has kicked in), and I also find consistently that a restore with AOMEI resets it to 50%. Restarts are fine and never seem to cause the issue.
On mine Windows 10 1809 (Spooky) decides to change the current Profile in the Intel HD Graphics Control Panel. i.e. it switches on the "Display Power Saving Technology".
This is one of the places for that setting, the one in Windows Power Options has gone.
The frequency now is about once per day instead of several times daily.
I have gone backwards and forwards with Intel Drivers which may, or may not, have affected that.
Mine also uses Intel graphics and unticking the power saving options is one of the first things I have to do when installing W10. If I leave it at the default then battery operation cause the graphics to crash big time in W10. This has been ongoing since day 1 with W10 (and I think also with W8.1)
I just leave the Intel driver W10 selects as being most suitable as I find once you start chasing drivers you are on a merry go round.
Microsoft Rolls Out Windows 10 19H1 Preview Build 18262Code:We fixed an issue resulting in the brightness sometimes resetting to 50% after a reboot.
Until MS releases a fix for 1809 version, create a task in task scheduler that will take care of the brightness at startup.
I did it and it works flawlesssly.
1. Run "C:\Windows\System32\taskschd.msc"
2. Click on tab Action then"Create Task"
3. I used "DisplayBrightness" as a name.
4. Select "Run whether user is logged on or not"
5. Check "Do not store password".
6. Select "Run with highest privileges"
7. Select "Configure for Windows 10".
8. Click on "Triggers" tab
9. Click on "New"
10. Choose "Begin the task: "At Startup"
11. Click on "Ok"
12. Click on the "Actions" tab
13. Click on "New"
14. Paste this command into the Program/Script Line: C:\Windows\System32\WindowsPowerShell\v1.0\powershell.exe "(Get-WmiObject -Namespace root/WMI -Class WmiMonitorBrightnessMethods).WmiSetBrightness(1,XX)" where XX is the percentage of the Display Brightness you wish. For example, 1,80 is for 80% brightness.
15. Click OK on the Windows message.
16. Click on OK.
17. Reboot pc.
Enjoy!
P.S. After reboot, brightness works ok and if you reopen task scheduler again under "Library" section, you will see that the task completed successfully (0x0).
This is a similar link:
Restart/reboot resets brightness from 100% down to 50% - Windows 10 Forums
I'm on the latest 17763.134 for a standard user.
It is not just a Bootup change it is also a 50% adaptive brightness change after that depending on the screen at the time, very irritating, both have started again after a recent cumulative update to the .134 subversion for standard users.
Currently fiddling with the Intel HD graphics control panel, saved profiles sometimes works but no consistency.
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