Windows & BSOD · high

How to fixWU-0x800b0100

Windows Update Error 0x800b0100

What this error means

WU-0x800b0100 shows up as a high-severity Windows operating system fault. No signature was present in the subject. This error indicates that the downloaded update files are missing digital signatures or have been corrupted, causing trust verification to fail. See the troubleshooting steps below for the fix.

Before you begin

Save open work and back up important files. Note any recent driver or hardware changes. If Windows cannot start, use the startup guide first.

Work through these checks

0 of 3 complete
01Run DISM RestoreHealth and System File Checker (SFC) to repair corrupted components.

Run DISM RestoreHealth and System File Checker (SFC) to repair corrupted components..

Use the instructions for your exact device and operating system. Check the manufacturer’s documentation before changing firmware, hardware, or system settings.

I need help
02Restart and rebuild the Cryptographic Services catalog directories.

Restart and rebuild the Cryptographic Services catalog directories..

Use the instructions for your exact device and operating system. Check the manufacturer’s documentation before changing firmware, hardware, or system settings.

I need help
03Purge the SoftwareDistribution download directory and re-initiate the update.

Purge the SoftwareDistribution download directory and re-initiate the update..

Use the instructions for your exact device and operating system. Check the manufacturer’s documentation before changing firmware, hardware, or system settings.

I need help

Possible causes

  • Interrupted downloads causing incomplete or corrupt file packages inside the update cache.
  • Corruption inside the Cryptographic Services database files responsible for verifying file signatures.
  • Third-party security software intercepting and modifying update files during download.