Symantec endpoint protection antivirus definitions not updating
You can configure Configuration Manager software updates to deliver definition updates to client computers.This is done by configuring automatic deployment rules.
The information in this topic can help you to select and configure these methods.
The SEPM shows old virus definitions in "Admin Server Activity logs may provide details on the nature of the failure.
One possible cause is that old or corrupted virus definitions present on the SEPM prevent the SEPM's ability to update the SEP clients with new virus definitions.
To update antimalware definitions, you can use one or more of the following methods: You can configure multiple definition update sources and control the order in which they are assessed and applied.
This is done in the Configure Definition Update Sources dialog box when you create an antimalware policy.