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The signature for Windows XP Professional Upgrade is invalid. The error code is 800b0100

Original title: Hi,  I was trying to install a Korean keyboard on the laptop that that is running XP Pro and found that I couldn't log in later. I want to recover or re-install XP but cannot find the CD.

I think that the keyboard failed to respond as the laptop would boot up to the log in screen but went into a loop when I typed my password, I can't find the original CD but did find what I thought was a copy I had backed up which had XP Pro + SP1 on it. I tried booting from this and tried to repair the installed files it now runs through the installation process until it reports the following:

The signature for Windows XP Professional Upgrade is invalid. The error code is 800b0100

No signature was present in the subject. This is a fatal error.

Hi,

Thank you for posting the query in Microsoft community forums!
I understand that you are facing issue while installing Windows XP. Do not worry; we will help you in resolving the issue.

What is the make and model of the computer?

To get the error "The signature for Windows XP Professional Upgrade is invalid. The error code is 800b0100" fixed, you may try the suggestions from the links:
"Invalid Boot.ini" or "Windows could not start" error messages when you start your computer
http://support.microsoft.com/kb/330184


You may try the steps from the link to install Windows XP on the computer.

How to perform an in-place upgrade (reinstallation) of Windows XP
http://support.microsoft.com/kb/978788

If you need further assistance with this issue or any other issues related to Windows Operating System, keep us posted. We will be happy to help you.

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Question Info

Last updated December 20, 2023 Views 1,415 Applies to: