The issue happens because the update package (Agent-Windows-9.5.3-2754.x86_64.zip) cannot be found from WWWListing and the DSR is downloading the 32-bit package instead of the 64-bit.

To resolve the issue:

1. Upgrade Deep Security Manager 9.0 SP1 Patch 4 to version 9.5 SP1.
2. Go to Administrator > Updates > Software > Local and import the update package (Agent-Windows-9.5.3-2754.x86_64.zip).
3. Navigate to Computer > Action.
4. Click Upgrade Agent Software to upgrade the DSR.