[Solved] Windows 10 Update Failed “Your device is missing important security and quality fixes.”

Problem: Windows 10 unable to perform Windows Update with error “Your device is missing important security and quality fixes.”, after clicking on “Check for updates” button still showing “You’re not up to date” message with same error message.

Windows 10 Update Error

Additionally, Windows 10 System Tray show Windows Update error icon with red exclamation mark as below.

Windows 10 System Tray show Update error icon with red exclamation mark

Content Summary

Solution 1: Enable Windows Update Advanced Option
Solution 2: Make sure Country or region setting is correct
Solution 3: Install Missing Windows 10 Update released September, 2018
Solution 4: Reset Windows Update History and Files
Solution 5: Update BIOS
Reference

Solution 1: Enable Windows Update Advanced Option

Step 1: Open Start > Settings > Update & Security.

Step 2: Click Advanced options link.

Step 3: Make sure Give me updates for other Microsoft products when I update Windows is checked.

Windows 10 Update Advanced Options Give me updates for other Microsoft products when I update Windows

Solution 2: Make sure Country or region setting is correct

Step 1: Open Start > Time & language > Region & language.

Step 2: Under Country or region, select the country you want to use from the drop-down menu.

Windows 10 Country or region setting

Step 3: Restart Windows.

Solution 3: Install Missing Windows 10 Update released September, 2018

Step 1: Visit Microsoft Update Catalog website to download stand-alone package for below update:

KB4457128: September 11, 2018—KB4457128 (OS Build 17134.285)

KB4456655: Servicing stack update for Windows 10, version 1803: September 11, 2018

KB4457146: Security update for Adobe Flash Player: September 11, 2018

KB4100347: Intel microcode updates

Step 2: Install downloaded stand-alone package.

Step 3: Restart Windows.

Solution 4: Reset Windows Update History and Files

Step 1: Open cmd.exe with Run as administrator option

Step 2: Type the following command:
net stop bits
net stop wuauserv
net stop appidsvc
net stop cryptsvc

Step 3: Open Windows Explorer and navigate to C:\Windows\SoftwareDistribution folder, right-click and choose Rename option. Change its name to SoftwareDistribution.old and apply the changes.

Step 4: Open cmd.exe with Run as administrator option

Step 5: Type the following command:
net start bits
net start wuauserv
net start appidsvc
net start cryptsvc

Solution 5: Update BIOS

Step 1: Perform BIOS and Chipset update. Refer to this article for [How to Access BIOS or Boot Menu using Windows 10 Recovery Advanced Startup]

Step 2: Restart and try to perform Windows Update again.

Reference

Microsoft Technet: Windows 10 update issue
Microsoft Community: Cumulative Update for Windows 10 version 1803 for x64 based Systems (KB4346783) (OS Build 17134.254)
Microsoft Community: windows 10 update problem