Windows Error 0x800F081F — Source Files Not Found

Windows Update error 0x800F081F means the source files for enabling a feature or installing an update could not be found. This guide covers everything you need to know about this topic, including common causes, step-by-step solutions, and answers to frequently asked questions.

Here are the key things to understand: CBS_E_SOURCE_MISSING — required source files not found. Common when enabling .NET Framework 3.5. Also occurs with optional Windows features. May need Windows installation media to resolve. Understanding these fundamentals will help you diagnose and resolve this issue more effectively.

The most common reasons this occurs include: Group Policy blocking Windows Update as repair source. Windows installation media not available. Corrupted component store. WSUS server not providing required files. Identifying the root cause is the first step toward finding the right solution.

To resolve this, follow these recommended steps: Enable "Contact Windows Update directly" in Group Policy. Use Windows ISO/USB: DISM /Online /Enable-Feature /FeatureName:NetFx3 /Source:D:\sources\sxs. Run DISM /Online /Cleanup-Image /RestoreHealth. Check WSUS settings in enterprise environments. If these steps do not resolve the issue, consider consulting additional resources or a qualified professional.

This article is part of our Windows Error Codes collection on Error Codes Wiki. We provide comprehensive, up-to-date information to help you find solutions quickly.