Something just updated requiring a reboot

A little message popped up saying a reboot is required to finish an installation. How do I find out what just installed on my machine. I had a quick look at the event viewer but couldnt see anything in there other than the machine starting up. Also checked installed updates but nothing recent there. Any ideas?

V1909 build 18363.535

Interesting read but I dont have Malwarebytes. Looked in Reliability and a Security update occurred 10 mins after the reboot. Reboot 22.48 Security update at 22.59. Still puzzled.

- - - Updated - - -

The process C:\Windows\System32\RuntimeBroker.exe (STUDIO-10X64) has initiated the restart of computer STUDIO-10X64 on behalf of user STUDIO-10X64\x_ban for the following reason: Other (Unplanned)
Reason Code: 0x0
Shut-down Type: restart
Comment:

Found this in event log but its not very explanitory.

These are some additional places besides reliability control panel and event viewer:

a) Windows updates
b) Downloads folder

zbook said:

These are some additional places besides reliability control panel and event viewer:

a) Windows updates
b) Downloads folder

Nothing stands out in those locations and I have updated my 32 bit machine and 64 bit laptop with windows update both installing a Defender update but no reboot required.

Open administrative powershell and copy and paste:

Code:

function Test-RebootRequired
{
    # Initialize result array
    $result = @{
        CBSRebootPending = (Get-ChildItem "HKLM:Software\Microsoft\Windows\CurrentVersion\Component Based Servicing\RebootPending" -ErrorAction SilentlyContinue).CBSRebootPending
        WindowsUpdateRebootRequired = (Get-Item "HKLM:SOFTWARE\Microsoft\Windows\CurrentVersion\WindowsUpdate\Auto Update\RebootRequired" -ErrorAction SilentlyContinue).WindowsUpdateRebootRequired
        FileRenamePending = (Get-ItemProperty "HKLM:SYSTEM\CurrentControlSet\Control\Session Manager" -Name PendingFileRenameOperations -ErrorAction SilentlyContinue).FileRenamePending
        SCCMRebootPending = $false
	}

    # Complete result Array with SCCM client status
    try 
    { 
        $util = [wmiclass]"\\.\root\ccm\clientsdk:CCM_ClientUtilities"
        $status = $util.DetermineIfRebootPending()
        if(($status -ne $null) -and $status.RebootPending){
            $result.SCCMRebootPending = $true
        }
    }catch{}

    # Normalize Result Array
    if ($result.CBSRebootPending -eq $null){ $result.CBSRebootPending = $false }
    if ($result.WindowsUpdateRebootRequired -eq $null){ $result.WindowsUpdateRebootRequired = $false }
    if ($result.FileRenamePending -eq $null){ $result.FileRenamePending = $false }

    #Return Reboot required
    return $result.ContainsValue($true)
}

Copied and pasted into admin PS but prompt just returned after pressing enter should I be looking for a variable?

It indicated that none of the 4 parameters were met for pending reboot.