Microsoft Security Client Error Code 0x800b0001 Posted on by Webmaster IT Support Forum › Forums › Antivirus › Microsoft › Windows Defender › Troubleshooting › Microsoft Security Client Error Code 0x800b0001 Tagged: 0x800b0001 This topic has 0 replies, 1 voice, and was last updated 7 years, 10 months ago by Webmaster. Viewing 0 reply threads Author Posts December 2, 2015 at 10:35 am #1472 WebmasterKeymaster When I try to start Windows Defender, I get this error: Microsoft security client error code 0x800b0001 I’ve downloaded another antivirus client, but can’t find why I get error 0x800b0001. Author Posts Viewing 0 reply threads You must be logged in to reply to this topic. Log In Username: Password: Keep me signed in Log In