Windows Troubleshooting Guide

Windows Reliability Monitor:
Reliability History Explained

A complete guide to using and analyzing the System Stability Monitor in Windows 10 and Windows 11 — diagnose crashes, application errors, and hardware failures like a pro.

⊞ Windows 10 ⊞ Windows 11 🛠 Built-in Tool ⏱ 10 min read 🆓 No Downloads Required
Section 01

What Is the Windows Reliability Monitor?

The Windows Reliability Monitor (officially called Reliability History) is a built-in diagnostic tool included in both Windows 10 and Windows 11. It provides a chronological, visual timeline of system stability events — including application crashes, hardware failures, Windows updates, software installs, and unexpected shutdowns — all in one place.

Unlike Event Viewer, which presents raw technical logs that can be overwhelming, Reliability Monitor was designed for everyday users. It assigns a Stability Index score from 1 to 10, calculated daily, giving you an at-a-glance measure of how stable your system has been over the past few weeks.

ℹ️
Key Fact Reliability Monitor has been part of Windows since Vista. The data it shows is derived from the Windows Management Instrumentation (WMI) service and is stored in the %ProgramData%\Microsoft\Windows\ReliabilityAnalysisComponent folder.

The tool is particularly valuable when your computer has started behaving erratically — freezing, crashing, or showing the Blue Screen of Death (BSOD) — but you are not sure where to start diagnosing the problem. Reliability Monitor lets you instantly correlate a crash with a recent software install or Windows update.

Section 02

How to Open Reliability Monitor in Windows 10 & 11

There are several ways to launch the Reliability Monitor. Choose whichever method suits you best:

🔍 Method 1 — Search Bar (Fastest)

  1. Click the Start button or press the Windows key.
  2. Type reliability or View reliability history in the search bar.
  3. Click the "View reliability history" result that appears at the top.

⚙️ Method 2 — Control Panel

  1. Open Control Panel (search for it or press Win + R and type control).
  2. Navigate to System and Security → Security and Maintenance.
  3. Expand the Maintenance section by clicking it.
  4. Click "View reliability history" in the bottom part of the section.

💻 Method 3 — Run Dialog

  1. Press Win + R to open the Run dialog.
  2. Type perfmon /rel and press Enter.

🖥️ Method 4 — Performance Monitor

  1. Press Win + R, type perfmon, and press Enter.
  2. In the left panel, expand Reports → System.
  3. Click "Reliability Monitor".
⚠️
Note If Reliability Monitor shows no data or says "Calculating reliability for this period," the RacTask scheduled task may be disabled. Re-enable it in Task Scheduler under Microsoft → Windows → RAC.
Section 03

Understanding the Reliability Monitor Interface

Once opened, the Reliability Monitor displays a clean timeline graph. Here is what each part of the interface means:

📊 Example Stability Index Timeline (30-day view)
8.2
W1
7.9
W2
7.2
W3
3.5
W4
5.5
W5
6.8
W6
7.7
W7
8.5
W8
Stable (7–10)
Moderate (4–6.9)
Unstable (1–3.9)

📐 Key Interface Elements

Element Description Interaction
Graph Area Timeline of the Stability Index over days or weeks Click any column to see events for that day
Days / Weeks toggle Switch between daily and weekly view Click "Days" or "Weeks" above the graph
Event Rows Rows for critical events, warnings, and informational items Icons appear on dates when events occurred
Details Pane Shows specific events for the selected date Click an event row entry for full details
Save Reliability History Exports an XML report of all stability data Link at the bottom-left of the window
View all problem reports Opens a full list of every reported problem Link at the bottom-left of the window
Section 04

Reading the Stability Index Score in Windows Reliability Monitor

The Stability Index is the core metric of Reliability Monitor. It is a rolling score calculated from reliability event data collected over the past 28 days. The score ranges from 1 (least stable) to 10 (most stable).

Windows uses a weighted decay algorithm — recent failures lower the score more than older ones, and the score gradually recovers over time if no new failures occur. A single BSOD can drop the score by 2–3 points instantly.

9–10: Excellent
10
7–8.9: Good
8
4–6.9: Fair
6
1–3.9: Poor
2.8
✅
Good to know A perfect score of 10 is rare on an active system and not necessarily the goal. Scores of 7 and above indicate a well-functioning system with no significant recurring issues.

The score is purely informational and not used by Windows to throttle performance or trigger any automatic action. Its value is in trend detection — a steadily declining score is a red flag that deserves investigation.

Section 05

Types of Events Tracked by Windows Reliability Monitor

Reliability Monitor categorizes all logged events into five distinct types. Understanding what each type means helps you prioritize what to investigate first.

🔴
Application Failures
App crashes, freezes, or hangs. The most common event type on typical systems.
💀
Windows Failures
BSODs (Stop errors), unexpected shutdowns, and OS-level crashes. Highest severity.
⚠️
Miscellaneous Failures
Hardware, driver, and service failures that don't fit the above categories.
🟡
Warnings
Non-critical issues like failed backups or Windows Update errors. No score impact.
🟢
Information Events
Successful updates, software installs/uninstalls. Helps correlate events to changes.
🔍
Diagnosis Tip When you see your stability score drop sharply, first check Information Events for software installations or updates on the same date. Crashes immediately following an update or install are very likely caused by that change.
Section 06

How to Analyze System Failures Using Reliability Monitor

Once you have Reliability Monitor open, follow this structured approach to identify and understand what is causing instability on your system:

🔎 Step-by-Step Analysis Workflow

  1. Identify the drop. Look at the graph for a significant dip in the Stability Index. Click that column to select the day.
  2. Review the event list. In the details pane below, read through all critical events (red X icons) listed for that date.
  3. Click "View technical details". For any event, click the link to open an expanded view with the faulting module name, error code, and process ID.
  4. Note the faulting application/module. The Faulting Module Name field tells you exactly which DLL or EXE caused the crash — this is your primary clue.
  5. Cross-reference with Information Events. Check if any software was installed or updated on the same day or the day before the crash.
  6. Search for the error online. Copy the Problem Signature or module name and search online for known fixes.
  7. Check for patterns. If the same application crashes repeatedly across multiple days, the problem is almost certainly within that application or its dependencies.

📋 Reading Technical Details

Field What It Means Where to Use It
Faulting Application The EXE or process that crashed Reinstall or update this app first
Faulting Module The DLL that actually caused the fault Search for "faulting module [name] fix"
Exception Code Hexadecimal crash reason (e.g., 0xc0000005) Decode at Microsoft Docs or StackOverflow
Stop Code (BSOD) The BSOD error name and code Search directly for the stop code string
OS Version Windows build number at crash time Check if the issue is build-specific
Section 07

Reliability Monitor in Windows 10 vs Windows 11: Key Differences

The core functionality of Reliability Monitor is identical in both Windows 10 and Windows 11, as it relies on the same underlying WMI data source. However, there are a few navigational and visual differences worth noting.

⊞ Windows 10 Win 10
Found via Control Panel → Security and Maintenance
Classic Control Panel UI navigation path
Security and Maintenance accessible from the system tray flag icon
Same graph and event tracking as Windows 11
Runs on builds 1507 through 22H2 unchanged
⊞ Windows 11 Win 11
Control Panel still exists but is harder to find via Settings UI
Search bar method (perfmon /rel) is more practical
The tool's own window design is unchanged
Reliability data resets after major Windows upgrades
Task Scheduler path for RacTask is the same
💡
Windows 11 Tip On Windows 11, the fastest way to open Reliability Monitor is always the search bar or Win + R → perfmon /rel. The Control Panel path still works but requires extra navigation steps compared to Windows 10.
Section 08

Common Errors Found in Reliability Monitor and How to Fix Them

🔵 Application Crash: ntdll.dll Faulting Module

When ntdll.dll is listed as the faulting module, it almost never means the file itself is corrupted. ntdll.dll is a core Windows system library — the real culprit is typically a buggy third-party DLL that loads into the crashing application. Common fixes include:

  1. Run sfc /scannow in an elevated Command Prompt to repair system files.
  2. Update or reinstall the faulting application entirely.
  3. Disable third-party shell extensions using ShellExView.
  4. Run Windows Memory Diagnostic to rule out RAM issues (mdsched.exe).

💀 Windows Failure: BSOD DRIVER_IRQL_NOT_LESS_OR_EQUAL

This is one of the most common BSODs and almost always points to a driver issue — typically a network adapter, USB, or GPU driver. Fixes:

  1. Note the driver filename shown in Reliability Monitor's technical details.
  2. Roll back the driver via Device Manager if it was recently updated.
  3. Download the latest driver directly from the hardware manufacturer's site.
  4. Run Driver Verifier (verifier.exe) to isolate the problematic driver.

⚠️ Windows Update Failures

Update failures appear as warnings and do not directly lower the Stability Index, but a repeatedly failing update can indicate underlying issues. Fix with:

  1. Run the Windows Update Troubleshooter from Settings → System → Troubleshoot.
  2. Clear the Windows Update cache by stopping the wuauserv service and deleting contents of C:\Windows\SoftwareDistribution\Download.
  3. Run DISM /Online /Cleanup-Image /RestoreHealth in an elevated Command Prompt.
🚨
Critical Warning If your Stability Index remains below 3 for more than a week despite troubleshooting, consider performing a Windows Reset (keeping your files) or checking your hard drive for imminent failure using CrystalDiskInfo before data loss occurs.
Section 09

Saving and Sharing a Reliability Report from Windows

Reliability Monitor allows you to export all collected stability data as an XML file, which is useful for sharing with IT support or keeping as a diagnostic record.

📤 How to Save Your Reliability History

  1. Open Reliability Monitor using any method described above.
  2. Click "Save reliability history" at the bottom-left corner of the window.
  3. Choose a destination folder and filename, then click Save.
  4. The exported file is in XML format and can be opened in any browser or shared via email.

📋 How to View All Problem Reports

  1. Click "View all problem reports" at the bottom of the Reliability Monitor window.
  2. This opens a full list showing every reported problem, grouped by application.
  3. Right-click any entry to copy details to the clipboard or check for solutions online.
🔒
Privacy Note The reliability report XML contains no personal files or data. It only includes application names, timestamps, error codes, and module names. It is safe to share with tech support.
Section 10

Limitations of Windows Reliability Monitor

While Reliability Monitor is a valuable first-stop tool, it has several notable limitations that every user should be aware of:

✓ Strengths

  • Zero setup — built into every copy of Windows 10 and 11
  • Visual timeline makes pattern recognition easy
  • Correlates crashes with installs and updates automatically
  • No technical knowledge needed to get started
  • Exportable reports for sharing with IT support
  • Works in real-time — data is updated daily

✗ Weaknesses

  • Data is reset after major Windows version upgrades
  • Only shows the last ~28 days of detailed history
  • Stability Index is not standardized or comparable between PCs
  • Does not capture all types of hardware failures (e.g., overheating)
  • Requires the RacTask scheduled task to be running
  • Less detail than Event Viewer for advanced troubleshooting
Section 11

Alternative Diagnostic Tools to Use Alongside Reliability Monitor

For deeper investigation beyond what Reliability Monitor provides, these complementary Windows tools are essential:

Tool How to Open Best For
Event Viewer eventvwr.msc Raw log data, custom filtering, security events
Windows Memory Diagnostic mdsched.exe Testing RAM for errors causing crashes
Performance Monitor perfmon.exe CPU, RAM, disk performance counters over time
Resource Monitor resmon.exe Real-time resource usage by process
SFC (System File Checker) sfc /scannow (admin CMD) Repairing corrupted Windows system files
DISM DISM /Online /Cleanup-Image /RestoreHealth Repairing the Windows image before running SFC
WhoCrashed Third-party download Human-readable analysis of BSOD dump files
CrystalDiskInfo Third-party download Monitoring hard drive and SSD health (S.M.A.R.T.)
Section 12

Frequently Asked Questions About Windows Reliability Monitor

Q Why does Reliability Monitor show no data or say "Calculating reliability"? ▼
This usually means the RACAgent scheduled task is disabled. Open Task Scheduler (taskschd.msc), navigate to Task Scheduler Library → Microsoft → Windows → RAC, and ensure the RacTask is enabled and set to run. Once re-enabled, data will begin populating within 24 hours. Also note that data resets after a major Windows feature update.
Q Can I delete or clear the Reliability Monitor history? ▼
There is no built-in button to clear history. However, you can delete the data files manually from %ProgramData%\Microsoft\Windows\ReliabilityAnalysisComponent\StateRepository. Alternatively, disabling and re-enabling the RacTask effectively resets data collection. Note that clearing history does not fix any underlying issues — it only removes the historical record.
Q Does a low Stability Index score affect my PC's performance? ▼
No. The Stability Index is a purely informational metric. Windows does not use it to throttle resources, limit features, or change any system behavior. A score of 1 and a score of 10 are treated identically by the operating system — the number only exists to help you assess system health at a glance.
Q Why does my Reliability Monitor show crashes for apps I've never heard of? ▼
Many background services, system components, and software updaters run silently and can crash without you ever noticing. Common examples include svchost.exe, MicrosoftEdgeUpdate.exe, WerFault.exe, and various antivirus components. If the application name is unfamiliar, search for it online — it is almost always a legitimate system or third-party background process.
Q How is Reliability Monitor different from Event Viewer? ▼
Reliability Monitor is a simplified, visual summary specifically focused on stability-impacting events (crashes, failures, installs). It is designed for casual users and gives a quick overview. Event Viewer captures a much broader range of system events — including security logs, service starts/stops, and application events — in raw format. For advanced troubleshooting, Event Viewer is more powerful; for a quick overview, Reliability Monitor is far easier to use.
Q Does Reliability Monitor work after upgrading from Windows 10 to Windows 11? ▼
After a major Windows upgrade (including Windows 10 → Windows 11), Reliability Monitor resets its history. The graph will start fresh from the date of the upgrade. Pre-upgrade events are not migrated. This is expected behavior and not a cause for concern. The tool will begin building a new history immediately after the upgrade completes.
Q Should I be worried if my Stability Index score is below 5? ▼
A score below 5 is worth investigating, but it is not always a sign of serious hardware or OS problems. A single application crashing repeatedly (such as a buggy game or browser) can pull the score down significantly. Review the specific events causing the drops — if they are all from one application, reinstalling that app may restore your score quickly. If Windows Failures (BSODs) are causing the low score, that warrants more urgent attention.

🎯 Key Takeaways

The Windows Reliability Monitor is one of the most underused yet genuinely useful tools built into Windows 10 and Windows 11. By providing a clear visual timeline of system stability events, it allows users of all skill levels to quickly identify what changed before a problem started — whether that is a software install, a Windows update, or a recurring application crash.

For routine maintenance, check Reliability Monitor once a month and investigate any sustained drops in the Stability Index. For active troubleshooting after a crash or BSOD, it should be your first stop before diving into the complexity of Event Viewer. Combined with tools like SFC, DISM, and Windows Memory Diagnostic, Reliability Monitor forms the backbone of any systematic Windows troubleshooting workflow.