LUA Download Tasks Fail with HTTP 416 Error Starting From June 1st, 2026

Products

• Endpoint Protection
• Endpoint Security
• Endpoint Security Complete

Issue/Introduction

Starting from June 1st, 2026, LiveUpdate Administrator (LUA) download tasks fail consistently. 

When this issue occurs, the following symptoms and error logs are observed:

LUA Event Log:

Failed to download file "xxx" while processing request ID "yyy".
The download job from source server "Symantec LiveUpdate" failed. Failed to download "xx" updates.

lua-application.log:

HTTP 416 (Range Not Satisfiable) errors are recorded when LUA attempts to execute download requests from the LiveUpdate server:

Fatal transport error in download: 416: could not find file to download - http://liveupdate.symantecliveupdate.com:80/...

 

LiveUpdate fails to update AV (Virus and Spyware) definitions on Symantec Endpoint Protection Manager (SEPM) and Symantec Endpoint Protection client (SEPC) environments as well.

lux.log (SEPM):

12:56:45.133669         Result Message: OK - catalog not available

log.lue (SEPC):

* Update failed for moniker {0F36F5AD-0A43-296F-7E43-B8D47066787B}, P: SEPC Virus R Definitions SDS Win64 (n64) 14.3 RU9, V: MicroDefsB.CurDefs, L: SymAllLanguages, install result code: 0xFFFFFF00.

Environment

• LUA 2.3.x
• SEPM/SEPC 14.3.x

Cause

LiveUpdate content distribution servers experienced an unexpected change that interrupted download operations for customers running LiveUpdate/LiveUpdate Administrator, causing affected download tasks to fail until the issue was resolved.

Resolution

The next definition update (20260601.002) corrected this issue.