Application and Software Troubleshooting

Lesson 17 · Application and Software Troubleshooting · Download .docx

Objectives

Diagnose and resolve missing DLL, compatibility, and permission errors
Use Event Viewer and Windows repair tools for application issues
Explain DISM, winget, and proper application uninstallation

Key terms

Missing DLL: Required shared library is absent; fix by reinstalling the app or runtime.
Visual C++ Redistributable: Microsoft runtime package providing DLL libraries required by many Windows applications.
Compatibility Mode: Windows feature running an older application as if on a previous OS version.
Run as Administrator: Elevates application privileges to resolve permission-related launch failures.
16-bit application: Cannot run natively on 64-bit Windows; no WOW64 support for 16-bit.
WOW64: Windows-on-Windows 64-bit — subsystem allowing 32-bit apps on 64-bit Windows.
DISM: Deployment Image Servicing and Management — repairs Windows component store when sfc fails.
winget: Windows Package Manager — native CLI tool for installing and managing applications.
Event Viewer Application log: Primary source for application crash details including faulting module and exception code.
Slow performance: Commonly caused by insufficient RAM or disk with less than 15% free space.
Uninstall: Settings → Apps or Control Panel → Programs and Features; removes all app components.
WSUS: Windows Server Update Services — enterprise tool for centralized Windows patch deployment.

The concept

DIAGNOSING APPLICATION ERRORS

Application errors follow predictable patterns. A 'missing DLL' error means the application cannot find a required shared library — reinstall the application or its runtime (e.g., Visual C++ Redistributable, .NET Framework). An 'Access Denied' error usually means the application needs elevated privileges — try Run as Administrator. When an application works on Windows 10 but fails on Windows 11, try Compatibility Mode (right-click executable → Properties → Compatibility tab).

For detailed crash information, open Event Viewer and navigate to Windows Logs → Application. Filter for Error level events around the time of the crash. The event details show the faulting module name, exception code, and memory address — information essential for identifying whether it is a bad DLL, driver conflict, or application bug.

WINDOWS REPAIR TOOLS

sfc /scannow scans and repairs Windows system files from the component store. If sfc reports it cannot repair files, run DISM /Online /Cleanup-Image /RestoreHealth first. DISM downloads replacement component files from Windows Update if needed and repairs the component store, after which sfc can complete its repair.

APPLICATION MANAGEMENT

winget is Windows' native command-line package manager. 'winget install <app>' installs from verified sources; 'winget upgrade --all' updates all managed apps. To properly uninstall, use Settings → Apps or Control Panel → Programs and Features — this runs the application's own uninstaller, removing all files, registry entries, services, and scheduled tasks. Deleting the Program Files folder leaves behind registry entries and services.

Note on 16-bit applications: 64-bit Windows includes WOW64 to run 32-bit applications but has no compatibility layer for 16-bit code. 16-bit applications simply cannot run on 64-bit Windows.

Worked examples

Example 1: An old CAD application crashes on launch with 'MSVCP140.dll not found'. Diagnosis: missing Visual C++ 2015-2022 Redistributable. Solution: download and install the Visual C++ Redistributable package from Microsoft's website. Relaunch the application.

Example 2: A user upgraded from Windows 10 to Windows 11 and their legacy accounting software no longer loads. Troubleshooting: right-click the .exe → Properties → Compatibility → check 'Run this program in compatibility mode for' and select Windows 10. If still failing, check Event Viewer Application log for specific error codes. If the app is 16-bit, it cannot run on 64-bit Windows 11 under any compatibility setting.

Common mistakes

Running sfc /scannow without elevation — must be from an Administrator command prompt.
Deleting the application folder instead of using the proper uninstaller — leaves registry entries and services.
Forgetting that 16-bit apps cannot run on 64-bit Windows — no compatibility setting can fix this architecture limitation.
Confusing sfc (OS system files) with chkdsk (disk file system errors) — different tools for different problem layers.
Assuming DISM replaces sfc — DISM repairs the component store that sfc uses; both tools serve distinct purposes.

Self-check

Try each one before you look. A miss here costs nothing and tells you exactly what to reread.

1. A 'missing DLL' error is fixed by:

2. Compatibility Mode is used to:

3. Application crash error details are found in:

4. DISM is used when:

5. winget is the native Windows tool for:

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