u/Chemical_Bee1495

Hi everyone!

I'm currently running OptiOS 10 LTSC 1809 (Windows 10 Enterprise LTSC 2019), a lightweight, optimized version of Windows 10 designed to reduce resource usage on older hardware.

My PC specs are:

• CPU: AMD Athlon II X2 (dual-core)
• RAM: 4 GB
• Storage: SSD
• OS: Windows 10 Enterprise LTSC 2019 (1809, Build 17763), customized with OptiOS.

The system runs really well, and I'd like to keep using it. However, there's one issue: Windows Defender Antivirus was completely removed from this custom Windows installation, presumably to reduce background processes and resource consumption.

I'd really like to restore Windows Defender so I can have free, continuous real-time antivirus protection without installing third-party software.

I've already done some troubleshooting using PowerShell:

• The WinDefend service doesn't exist.
• Get-MpComputerStatus is not recognized.
• The usual Windows Defender directories are missing.
• I couldn't find MsMpEng.exe or MpCmdRun.exe.
• Some Defender-related components still exist in C:\Windows\WinSxS, including MpClient.dll.
• DISM reports no component store corruption.

From what I understand, Defender wasn't simply disabled; its main components were actually removed from the system.

My main question is: Is there any way to reinstall or restore Microsoft Defender Antivirus without completely reinstalling Windows?

I'm particularly interested in knowing:

• Whether there's an official Microsoft package, script, or tool that can restore the missing Defender components and services.
• Whether it's possible to extract and restore Defender from an original Windows 10 Enterprise LTSC 2019 ISO.
• Whether anyone has successfully restored Defender on a stripped-down or debloated Windows installation.
• Whether this can be done without undoing most of the system's optimizations.

I understand that Microsoft provides Defender update packages for offline Windows installation images, but I'm not sure whether those could help restore a completely removed installation.

I'm willing to experiment, even if there's some risk of breaking Windows, since this is a fresh installation with no important files or data to lose.

Ideally, I'd like to keep OptiOS and restore only the components necessary for Defender to work.

Any advice, technical guidance, or personal experience with this would be greatly appreciated!

Thanks in advance!

Hi everyone!

I'm looking for recommendations for a lightweight antivirus that offers free, permanent real-time/background protection, similar to Windows Defender.

I'm using an old PC with the following specs:

• OS: Windows 10 Enterprise LTSC 2019 (1809, Build 17763), modified/optimized version called OptiOS.
• CPU: AMD Athlon II X2 (dual-core).
• RAM: 4 GB.
• Storage: SSD.

The main issue is that Windows Defender Antivirus was completely removed from this customized Windows installation, not just disabled.

I've already checked through PowerShell, and the WinDefend service, main executable files, and other essential components are missing. Restoring Defender doesn't seem straightforward without repairing or reinstalling Windows, which I'd prefer to avoid because I want to keep the optimizations.

I've looked into Malwarebytes and Kaspersky, but the versions I've found either offer a limited Premium trial or don't provide permanent real-time protection for free.

What I'm looking for:

1. A genuinely free antivirus with continuous real-time/background scanning, not just manual scans.
2. Something lightweight enough for an old dual-core CPU with 4 GB of RAM.
3. Alternatively, a legitimate way to get a free Premium license, an extended trial, or another solution that provides the same protection without a subscription.
4. If possible, a way to restore the original Windows Defender without reinstalling Windows or undoing the system optimizations.

I'm not expecting top-tier performance, just decent protection against malware and viruses without significantly slowing down the PC.

Any recommendations or advice would be greatly appreciated!