Display brightness at max after 1803 update

Thanks for the information Carlo!

Microsoft indeed seems to have released a patch that should solve the brightness bug and several other issues:

Microsoft June 2018 Patch Tuesday - source: Windows Central, 12 June 2018 

"For those on the latest Windows 10 release, the April 2018 Update,  today's fixes are rolling out as KB4284835 (build 17134.112).  And while this rollout addresses a number of bugs,

it also contains a crucial fix for an issue affecting brightness controls on some laptops.

This seems to have been most noticeable on HP EliteBooks, but you should see an improvement if you've experienced issues on other laptops as well."

(see also Microsoft June 2018 Patch Tuesday Fixes 50 Security Issues - BLEEPINGCOMPUTER )

Did not try it myself, allready wasted so much time and haven't got the courage yet.

It is nice Carlo from Italy shared this here on Microsoft Community forum, but;

how come Microsoft did not post this solution / patch information here ?!!

Many Windows 10 laptop users suffer this problem and are confused, also here in my small social circle at The Netherlands a lot of people got affected.

Causing them to think update 1803 went wrong, suspected some fawlty hardware or even went to a computer-repair shop.

We all make mistakes, but: Microsoft please communicate with your customers!

Not only update us on the solution but also the moment you become aware a serious bug is caused by a Microsoft Update.

It would prevent a lot of uncertainty, waste of time and frustrations.

Thank you.

Thank you Riccardo.

This solution from Ferdz Amp solved my problem.

For those still encountering this issue, I recommend that you follow these steps and see if the issue persists:

1. In Windows start search box, type in regedit and hit Enter.
2. Navigate to the following key:
   • HKEY_LOCAL_MACHINE/SYSTEM/ControlSet001/Control/Class/ 4d36e968-e325-11ce-bfc1-08002be10318 /0000
3. Double-click the item of FeatureTestControl, set the hexadecimal value to "fb20", and click OK.
4. Reboot your computer to reflect the changes.

Registry Disclaimer: The steps mentioned here includes system registry modification. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow the steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base: Article ID 322756.

Let me know how it goes.

The written location for FeatureTestControl was different on my system. The location was:

• HKEY_LOCAL_MACHINE\SYSTEM\ControlSet001\Control\Class{4d36e968-e325-11ce-bfc1-08002be10318}\0001

Please be aware that after doing this edit, selecting the lowest level of brightness will turn off your screen. This also means that if you are running on battery (laptop) and you select the power mode "Best battery life" or Windows automatically switches to "Best battery life" upon unplugging the charger, your screen will be turned OFF! This is not a major concern since you can just turn up the brightness to the next lowest level via the FN+F3 (key combo might differ on other laptop brands) keyboard control shortcut and the screen will be turned back ON.

Taken from here:

https://answers.microsoft.com/en-us/windows/forum/windows_10-update/screen-brightness-stuck-at-maximum-after-updating/2c364180-cab4-4704-b07f-701a1bac89a5?tm=1525126129348

Thank's finally solved..... best regard.... keep sharing.....

THIS IS WHAT FIXED THE ISSUE FOR ME (Date: 23rd May 2018):

1. I opened Device Manager. 
2. Noticed that Display Adapters section was reporting problem (showing exclamation sign) for the "Intel HD Graphics 620". (This solution may work for other onboard graphics too).
3. I right clicked on that and chose "Update driver" option. 
4. On the pop-up window, I chose "Search automatically for updated driver software" option. 
5. Windows searched and automatically installed the driver software over Internet and the Brightness Controls started working again immediately (without restarting the PC). 
6. Device Manager also stopped reporting problem with Display Adapter.

I hope this helps some of you if not all of you.

Yeah, it's an asterisk.

OS Name    Microsoft Windows 10 Home

Version    10.0.17134 Build 17134

Other OS Description     Not Available

OS Manufacturer    Microsoft Corporation

System Name    

System Manufacturer    TOSHIBA

System Model    Satellite M645

System Type    x64-based PC

System SKU    *

Processor    Intel(R) Core(TM) i5 CPU       M 460  @ 2.53GHz, 2534 Mhz, 2 Core(s), 4 Logical Processor(s)