Browser & Application Troubleshooting

CompTIA A+ 220-1201 & 220-1202

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1 Introduction & Exam Overview

About the CompTIA A+ Certification Exam Domains & Study Strategy

2 Core 1 Domain 1: Mobile Devices (13%)

Laptop Hardware & Components Laptop Features & Display Types Mobile Device Connectivity & Accessories Mobile Operating System Features Mobile Device Synchronization & Data Transfer

3 Core 1 Domain 2: Networking (23%)

TCP/IP Fundamentals & the OSI Model Common Ports & Protocols Wireless Networking Standards Network Hardware & Devices Network Configuration & Internet Connections Network Types & Topologies

4 Core 1 Domain 3: Hardware (25%)

Cables & Connectors RAM Types & Storage Devices Motherboards, CPUs & Power Supplies Printers & Multifunction Devices Peripheral Devices & Expansion Cards Network Cable Tools & Testing

5 Core 1 Domain 4: Virtualization & Cloud Computing (11%)

Virtualization Concepts Cloud Computing Models & Services Client-Side Virtualization in Practice

6 Core 1 Domain 5: Hardware & Network Troubleshooting (28%)

CompTIA Troubleshooting Methodology Hardware Troubleshooting Network Troubleshooting Printer Troubleshooting Display & Mobile Device Troubleshooting

7 Core 2 Domain 1: Operating Systems (28%)

Windows Editions & Features Windows Administrative Tools & Utilities Windows Command Line & PowerShell macOS & Linux Basics Windows Networking & File Sharing Windows Installation & Upgrade Methods

8 Core 2 Domain 2: Security (28%)

Physical & Logical Security Measures Malware Types & Threat Mitigation Wireless & Network Security Encryption & Data Protection

9 Core 2 Domain 3: Software Troubleshooting (23%)

Windows OS Troubleshooting Mobile OS & Application Troubleshooting Browser & Application Troubleshooting

10 Core 2 Domain 4: Operational Procedures (21%)

Documentation & Change Management Backup & Recovery Methods Safety & Environmental Procedures Scripting & Remote Access Technologies Privacy, Licensing & Organizational Policies

Browser & Application Troubleshooting

Key Takeaways Explain This Topic AI

Browser slowness, pop-ups, redirects, and changed homepages usually trace to malicious extensions / potentially unwanted programs (PUPs) or a corrupt cache — disable extensions and clear cache before deeper fixes.

Always install a browser from the official source and watch for rogue certificate warnings, redirection to invalid certificates, and untrusted root CAs — never click through a certificate error on a public site.

Use Compatibility Mode (Properties → Compatibility) to run legacy apps on newer Windows; 64-bit Windows runs 32-bit apps from C:\Program Files (x86) but cannot run 16-bit apps.

Windows Update failures are commonly fixed by the Update Troubleshooter , clearing the SoftwareDistribution cache, freeing disk space, and running DISM + sfc .

Install failures map to clear causes: insufficient space, missing administrator rights, 32-bit vs 64-bit mismatch, a missing .NET / Visual C++ runtime , or antivirus blocking the installer.

Last updated: June 2026

Browser Issues and Security Symptoms

The browser is the single most malware-exposed application on a PC, so CompTIA pairs browser troubleshooting tightly with security. The Core 2 objectives explicitly call out browser-related security alerts you must recognize.

Symptom Likely Cause Fix

Slow / unresponsive browser Too many tabs, heavy or malicious extensions, low RAM Close tabs, disable extensions, restart browser

Constant pop-ups / redirects Adware extension or hijacked settings Remove suspicious extensions, reset settings, run antimalware

Homepage / default search changed and won't revert Browser hijacker / PUP Reset browser settings, remove PUP, scan

Certificate warning on a site Expired/invalid cert, wrong PC date/time , or attacker Verify date/time; do not proceed on public sites

"Untrusted root CA" or unexpected cert Rogue or self-signed certificate, possible MITM Investigate; accept only for known internal sites

Can't reach one specific site DNS, firewall, or the site is down Try another browser, ipconfig /flushdns , check firewall

Named Exam Concepts: Browser Security Settings

Trusted vs. untrusted sources / certificates — only install browsers and extensions from the official vendor site ; a download from a search-ad clone is a classic infection vector.

Invalid / expired certificate warnings — most often caused by the PC clock being wrong ; fix the date/time first.

Pop-up blockers, password managers, and private/secure browsing are legitimate settings the exam expects you to configure rather than disable.

Browser Reset Ladder

Clear browsing data — cache, cookies, history.

Disable all extensions , then re-enable one at a time to find the offender.

Reset settings to default (homepage, search engine, new tab).

Reinstall the browser from the official site if a hijacker persists.

Create a fresh browser profile if a corrupt profile is the cause.

Application Compatibility and Architecture
Compatibility Mode

When a legacy program built for an older Windows release misbehaves on Windows 10/11, use Compatibility Mode rather than downgrading the OS:

Right-click the program's .exe (or shortcut) → Properties .

Open the Compatibility tab.

Check "Run this program in compatibility mode for:" and pick the target Windows version (for example, Windows 7).

Optionally enable "Run this program as an administrator" for apps that expect elevation.

Click Apply and test. The Program Compatibility Troubleshooter can auto-detect settings if you are unsure.

32-bit vs. 64-bit (x86 vs. x64)

Fact Detail
64-bit Windows runs Both 64-bit and 32-bit applications
32-bit Windows runs 32-bit applications only (and is capped near 4 GB RAM )
64-bit app install path C:\Program Files
32-bit app install path C:\Program Files (x86) (the WoW64 subsystem)
16-bit legacy apps Will not run on 64-bit Windows

" This app can't run on your PC " frequently means an architecture mismatch — a 64-bit installer on 32-bit Windows, or an app whose minimum OS the machine does not meet. CompTIA also expects you to confirm the application's system requirements (RAM, CPU, free disk, dedicated GPU) before blaming the OS, and to know that some apps require OS-specific builds even across editions of Windows.

Windows Update and Installation Failures
Windows Update Repair

Update failures are common A+ scenario questions. Start with the built-in Windows Update Troubleshooter (Settings → System → Troubleshoot), note any error code , then escalate.

Issue Fix
Update stuck downloading Run the Troubleshooter; clear the SoftwareDistribution cache
Update fails repeatedly Record the error code, run DISM /RestoreHealth then sfc /scannow

Feature update fails Free disk space (a feature update needs roughly 20 GB+ ), disconnect non-essential peripherals

New driver issue after update Roll back the driver in Device Manager, or use System Restore

Clearing the update cache (the canonical procedure):

Open an administrator Command Prompt.

net stop wuauserv — stop the Windows Update service.

net stop bits — stop the Background Intelligent Transfer Service.

Delete the contents of C:\Windows\SoftwareDistribution\Download .

net start wuauserv then net start bits .

Re-run Windows Update.

Application Installation Failures

Error Cause Fix
"Not enough disk space" Full system drive Run Disk Cleanup , clear temp files
"Administrator privileges required" No elevation Right-click installer → Run as administrator
"This app can't run on your PC" 32/64-bit or OS mismatch Get the correct architecture/build
Installer hangs or crashes Conflict or AV block Close apps, temporarily disable real-time AV, retry
"Another installation is in progress" msiexec lock Wait, or restart Windows Installer service
Missing .NET or Visual C++ Redistributable Absent runtime Install the required Microsoft runtime, then retry

Exam trap: Disabling antivirus to complete an install is acceptable only temporarily and only for a trusted installer — re-enable real-time protection immediately afterward. Permanently disabling AV is always the wrong answer.