Windows 8.1 won't update

This is really strange. The file which tried to install and failed is this one: https://www.microsoft.com/en-us/download/details.aspx?id=51917

What you should have got was this one:

https://www.microsoft.com/en-us/download/details.aspx?id=51833

They both have the same KB3148198 number but the first one is for the 32-bit version of Windows 7 while the second one is for 8.1 and 64-bit.

Just to clarify, you do have a 64-bit version of Windows 8.1 don't you? If you're not sure, right click the Start button and click System. It will tell you in the section called System which it is.

Yes its 64 bit windows 8.1

OK, can you try and install the update manually using IE and see what happens.

Could you also post another Event Viewer log file for a different update which failed to install.

Tried updating KB3148198 with IE but it still says its not applicable for this computer.  Here is another WUSA log:

Log Name:      Setup

Source:        Microsoft-Windows-WUSA

Date:          30/04/2016 16:35:02

Event ID:      4

Task Category: None

Level:         Warning

Keywords:     

User:          PADDLING\jason

Computer:      paddling

Description:

Windows update Security Update for Windows (KB3146723) requires a computer restart to complete the installation. (Command line: ""C:\Windows\system32\wusa.exe" "C:\Users\jason\AppData\Local\Microsoft\Windows\INetCache\IE\JYXQZG0B\Windows8.1-KB3146723-x64.msu" ")

Event Xml:

<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">

  <System>

    <Provider Name="Microsoft-Windows-WUSA" Guid="{09608C12-C1DA-4104-A6FE-B959CF57560A}" />

    <EventID>4</EventID>

    <Version>0</Version>

    <Level>3</Level>

    <Task>0</Task>

    <Opcode>0</Opcode>

    <Keywords>0x8000000000000000</Keywords>

    <TimeCreated SystemTime="2016-04-30T15:35:02.863363000Z" />

    <EventRecordID>6332</EventRecordID>

    <Correlation />

    <Execution ProcessID="2116" ThreadID="2120" />

    <Channel>Setup</Channel>

    <Computer>paddling</Computer>

    <Security UserID="S-1-5-21-1702973034-409182297-3209008616-1002" />

  </System>

  <EventData>

    <Data Name="UpdateTitle">Security Update for Windows (KB3146723)</Data>

    <Data Name="CommandLine">"C:\Windows\system32\wusa.exe" "C:\Users\jason\AppData\Local\Microsoft\Windows\INetCache\IE\JYXQZG0B\Windows8.1-KB3146723-x64.msu" </Data>

  </EventData>

</Event>

Tried installing KB3148198 with IE but still says not applicable for this computer.

Here is another WUSA:

Log Name:      Setup

Source:        Microsoft-Windows-WUSA

Date:          30/04/2016 16:30:28

Event ID:      3

Task Category: None

Level:         Error

Keywords:     

User:          PADDLING\jason

Computer:      paddling

Description:

Windows update  could not be installed because of error 2149842967 "" (Command line: ""C:\Windows\system32\wusa.exe" "C:\Users\jason\AppData\Local\Microsoft\Windows\INetCache\IE\410A72P1\Windows8.1-KB3138602-v2-x86.msu" ")

Event Xml:

<Event xmlns="http://schemas.microsoft.com/win/2004/08/events/event">

  <System>

    <Provider Name="Microsoft-Windows-WUSA" Guid="{09608C12-C1DA-4104-A6FE-B959CF57560A}" />

    <EventID>3</EventID>

    <Version>0</Version>

    <Level>2</Level>

    <Task>0</Task>

    <Opcode>0</Opcode>

    <Keywords>0x8000000000000000</Keywords>

    <TimeCreated SystemTime="2016-04-30T15:30:28.638452600Z" />

    <EventRecordID>6329</EventRecordID>

    <Correlation />

    <Execution ProcessID="4692" ThreadID="4016" />

    <Channel>Setup</Channel>

    <Computer>paddling</Computer>

    <Security UserID="S-1-5-21-1702973034-409182297-3209008616-1002" />

  </System>

  <EventData>

    <Data Name="UpdateTitle">

    </Data>

    <Data Name="ErrorCode">2149842967</Data>

    <Data Name="ErrorString">

    </Data>

    <Data Name="CommandLine">"C:\Windows\system32\wusa.exe" "C:\Users\jason\AppData\Local\Microsoft\Windows\INetCache\IE\410A72P1\Windows8.1-KB3138602-v2-x86.msu" </Data>

  </EventData>

</Event>