Windows Update Error 0x800b0100

What is WU-0x800b0100?

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.

Common 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.

Step-by-Step Fix Guide

• 1
  Run DISM RestoreHealth and System File Checker (SFC) to repair corrupted components.
• 2
  Restart and rebuild the Cryptographic Services catalog directories.
• 3
  Purge the SoftwareDistribution download directory and re-initiate the update.

Commands & Diagnostics