Debugging Unity & Unreal Games: Complete Troubleshooting Guide

Game crashes are among the most frustrating issues for both players and developers. When your Unity or Unreal Engine game abruptly terminates, often with little warning, it signals a deeper problem that requires a systematic debugging approach. This guide will walk you through diagnosing and resolving runtime crashes in games built with these powerful engines.

What This Guide Covers

This comprehensive guide is designed for developers encountering runtime crashes in games developed with Unity (versions 6.3.8f1, 6.4.9f1) and Unreal Engine (versions 4, 5.0 to 5.7.1). We’ll cover common symptoms, deep-dive into root causes like hardware instability, software conflicts, engine-specific bugs, and environment issues. You’ll learn essential and advanced debugging techniques, including Visual Studio 2026 Community integration, and best practices for preventing future crashes, especially considering Linux build considerations.

Common Game Crash Symptoms

A game crash can manifest in various ways, but the outcome is always an unexpected termination of the application. Identifying the specific symptoms can provide crucial clues for diagnosis.

An Unreal Process Has Crashed: UE4-MyGameName Fatal Error!

This is the canonical error message for many Unreal Engine crashes, often accompanied by a detailed crash reporter window.

Other common symptoms include:

• Sudden Application Closure: The game window disappears without any error message.
• Screen Lock-up with Pattern/Buzzing: The display freezes, often showing distorted graphics or a repeating pattern, accompanied by a continuous buzzing sound from speakers. This usually indicates a severe hardware or driver issue.
• Blue Screen of Death (BSOD): A critical system error, often pointing to kernel-level driver issues or severe hardware failure.
• Editor Crashes: The Unity or Unreal Editor itself crashes, especially during play mode or asset compilation.
• Specific Error Dialogs: Beyond the Unreal crash reporter, you might see OS-level error messages about memory access violations or unhandled exceptions.
• Consistent Crashes After Specific Actions: The game crashes reliably after performing a certain action, loading a specific level, or interacting with a particular object.
• Intermittent Crashes: The game crashes seemingly randomly after varying periods of gameplay, often indicating resource exhaustion or subtle timing issues.

Root Cause: Hardware Instability (PSU, Video Memory)

Hardware instability is a frequent, yet often overlooked, cause of game crashes, especially in resource-intensive Unity and Unreal Engine titles. These engines push hardware to its limits, making underlying issues more apparent.

Why it happens:

• Power Supply Unit (PSU) Failure/Insufficiency: A failing or undersized PSU cannot consistently deliver stable power to all components, especially the GPU and CPU, when they are under heavy load. When the game demands peak power, erratic power flow can cause components to momentarily lose stability, leading to system shutdowns or application crashes. The Search Evidence indicates that “erratic power flow to the motherboard” can cause Unity to shut down.
• Video Memory (VRAM) Issues:
  • Overheating: Overclocked or poorly cooled GPUs can cause VRAM to overheat. When VRAM reaches critical temperatures, it can lead to data corruption, graphical artifacts, and ultimately, a crash as the GPU driver attempts to recover or fails entirely.
  • Insufficient VRAM: While less common for crashes (more for performance drops), if a game attempts to allocate more VRAM than available, it can lead to memory access violations or driver-level failures.
  • Faulty VRAM Modules: Physical defects in the GPU’s memory modules can cause data corruption that the game engine cannot handle, resulting in a crash.
• CPU/RAM Instability: Overclocked or faulty CPU/RAM can also lead to data corruption or incorrect instruction execution, which manifests as crashes in any demanding application, including games.

Root Cause: Software & Driver Conflicts (Graphics Drivers, Virtualization)

Software and driver conflicts are a common culprit behind game instability, particularly with the complex rendering pipelines of Unity and Unreal Engine.

Why it happens:

• Outdated, Corrupt, or Incompatible Graphics Drivers: Graphics drivers are the interface between your game and the GPU.
  • Outdated drivers may lack optimizations or bug fixes for newer game engines or APIs (DirectX, Vulkan).
  • Corrupt installations can lead to partial functionality or incorrect behavior.
  • Incompatible drivers (e.g., installing a driver meant for a different OS version or GPU model) can cause rendering errors, memory leaks, and ultimately, crashes. The Search Evidence shows users trying to “uninstalling and reinstalling my graphic drivers” as a first step.
• Virtualization Features (Hyper-V, WSL, VirtualBox): Modern operating systems often include virtualization features (like Windows’ Hyper-V, Virtual Machine Platform, or Windows Subsystem for Linux - WSL).
  • Resource Contention: These features can reserve significant system resources (CPU, RAM) or alter how the kernel manages hardware access, potentially starving the game of critical resources or introducing latency.
  • Anti-Cheat Conflicts: Some game anti-cheat systems detect virtualization environments as potential cheating vectors and may trigger crashes or prevent the game from launching. The Search Evidence explicitly mentions a Unity game crashing until “all virtualization-related features off.”
• Conflicting Background Applications: Overlays (Discord, Steam, GeForce Experience), antivirus software, or other resource-intensive applications can interfere with game processes, leading to crashes.
• Operating System Issues: Corrupt system files, pending OS updates, or specific OS configurations can sometimes lead to instability for certain applications.

Root Cause: Engine-Specific Bugs (Null References, Stack Overflows)

Even with stable hardware and drivers, bugs within your game’s code, or sometimes the engine itself, can cause crashes. These are often logical errors that lead to critical runtime exceptions.

Why it happens:

• Null References / Null Pointer Dereferences: This is arguably the most common crash cause in object-oriented programming.
  • Unity (C#): A NullReferenceException occurs when your code attempts to access a member (method or property) of an object variable that currently holds a null value. This means the variable was declared but never assigned an instance of an object, or the object it referenced was destroyed. For example, myGameObject.GetComponent<MyScript>().DoSomething() will crash if myGameObject is null or if GetComponent<MyScript>() returns null.
  • Unreal Engine (C++): A nullptr dereference occurs when you try to access data or call a method on a pointer that points to nothing (memory address 0). This is a critical error that the OS typically catches as an access violation, leading to a crash. Unreal’s CHECK_VALID or IsValid() macros are designed to mitigate this, but direct pointer usage can still lead to issues.
• Stack Overflows:
  • Infinite Recursion: A function that calls itself (directly or indirectly) without a proper base case or termination condition will continue to push new stack frames onto the call stack until it consumes all available stack memory. This results in a stack overflow crash.
  • Excessive Local Variable Allocation: While less common, allocating extremely large arrays or objects on the stack (as local variables) can also exhaust stack memory. This is more prevalent in C++ (Unreal) than C# (Unity), where large objects are typically allocated on the heap. The Search Evidence mentions “Stack overflow problems” in Unreal Engine C++.
• Memory Leaks / Out-of-Memory (OOM): While often leading to performance degradation first, severe memory leaks (where allocated memory is never freed) can eventually exhaust all available RAM, causing the OS to terminate the game process.
• Race Conditions / Threading Issues: In multi-threaded code, if multiple threads access and modify shared data without proper synchronization, it can lead to corrupted data or deadlocks, which can manifest as unpredictable crashes.

Root Cause: Environment & Build Configuration Issues

The environment in which your game runs, and how it was built, can introduce subtle issues that lead to crashes, especially when deploying to different platforms or configurations.

Why it happens:

• Missing or Incorrectly Linked Libraries/Plugins:
  • Unreal Engine: When building for a specific platform (e.g., Linux DebugGame), if required plugins or external libraries are not correctly packaged or linked, the game executable will fail to find them at runtime, leading to a crash on startup or when the missing component is accessed. The Search Evidence highlights an issue where a “DebugGame built with UE 5.4.1 engine on Linux - cannot find plugins.”
  • Unity: Similar issues can arise with native plugins (DLLs, .so files), where incorrect platform settings or missing dependencies prevent them from loading.
• Incorrect Build Configuration:
  • Debug vs. Release Builds: Debug builds often include assertions, extra logging, and less aggressive optimizations. Running a Debug build in a production environment or without debug symbols can lead to crashes that wouldn’t occur in a Release build, or make them harder to diagnose. Conversely, Release builds can sometimes mask issues that only appear due to optimizations.
  • Development vs. Shipping Builds: Unreal Engine has specific build configurations (Development, Shipping). Shipping builds strip out many debugging features, making crashes harder to diagnose if they only occur in that configuration.
• Editor Version Mismatches: Developing a project with one engine version (e.g., Unity 6.3.8f1) and then attempting to open or build it with a different, incompatible version (e.g., Unity 6.4.9f1) can lead to unexpected behaviors, asset corruption, or editor crashes. The Search Evidence mentions “Weird errors blocking debug mode from Visual Studio with Unity 6-4.9f1” after updating from 6.3.
• Corrupt Project Files or Assets: Damaged project files, corrupted assets, or incorrect asset imports can cause the engine to encounter unhandleable data during loading or runtime, leading to a crash.
• OS-Specific Quirks (Linux Considerations): Building and deploying games on Linux often requires careful attention to case sensitivity in file paths, correct library dependencies (ldd can help), and specific compiler/toolchain versions that might differ from Windows or macOS development environments.

Essential Debugging Tools & Techniques

Effective debugging relies on a systematic approach and the right tools to peer into your game’s execution.

1. In-Engine Logging (Debug.Log, UE_LOG)
   • Purpose: The most basic and often most effective way to track program flow and variable states.
   • Unity:

        using UnityEngine;

        public class MyScript : MonoBehaviour
        {
            public GameObject targetObject;

            void Start()
            {
                if (targetObject == null)
                {
                    Debug.LogError("Target object is null in Start!");
                    // Crash prevention: return or handle gracefully
                    return;
                }
                Debug.Log("MyScript started on " + gameObject.name);
                Debug.LogFormat("Target object name: {0}", targetObject.name);
            }

            void Update()
            {
                // Log only when specific conditions are met to avoid spam
                if (Input.GetKeyDown(KeyCode.Space))
                {
                    Debug.LogWarning("Space key pressed!");
                }
            }
        }
 

- **Unreal Engine:**

        #include "MyActor.h"
        #include "Engine/Engine.h" // For GEngine->AddOnScreenDebugMessage

        AMyActor::AMyActor()
        {
            PrimaryActorTick.bCanEverTick = true;
        }

        void AMyActor::BeginPlay()
        {
            Super::BeginPlay();
            UE_LOG(LogTemp, Log, TEXT("MyActor %s has begun play."), *GetName());

            if (!MyComponent) // Example: check for a component pointer
            {
                UE_LOG(LogTemp, Error, TEXT("MyComponent is null in BeginPlay for %s!"), *GetName());
                // Crash prevention: return or handle gracefully
                return;
            }

            // On-screen debug message (editor/development builds only)
            if (GEngine)
            {
                GEngine->AddOnScreenDebugMessage(-1, 5.f, FColor::Red, FString::Printf(TEXT("Actor %s started!"), *GetName()));
            }
        }
 

- **Technique:** Sprinkle logs strategically around suspicious code paths. Use different log levels (Info, Warning, Error) to categorize messages. Check the Unity Console or Unreal Output Log (`~` key in editor/development builds) frequently.

2. Breakpoints and Stepping

   • Purpose: Halt execution at a specific line of code and inspect the program’s state (variables, call stack).
   • Technique: Set breakpoints in your C# (Unity) or C++ (Unreal) code within Visual Studio 2026 Community. When execution hits a breakpoint, the game pauses. Use “Step Over” (F10) to execute the current line and move to the next, “Step Into” (F11) to enter a function call, and “Step Out” (Shift+F11) to exit the current function.
   • Inspection: While paused, hover over variables to see their values, or use the “Watch” and “Locals” windows in Visual Studio.

3. Call Stack Analysis

   • Purpose: Understand the sequence of function calls that led to the current point of execution or a crash.
   • Technique: When a crash occurs or a breakpoint is hit, the “Call Stack” window in Visual Studio (or the Unity Console’s stack trace) shows the chain of function calls. This is invaluable for tracing back from the point of failure to the original cause. Look for your own code in the stack trace; engine code might be involved, but your code often triggers the error.

4. Unity Inspector & Unreal Details Panel

   • Purpose: Visually inspect and modify component properties and object states at runtime.
   • Unity: Select a GameObject in the Hierarchy during Play Mode. The Inspector will show all attached components and their public/serialized fields. You can modify values in real-time to test different scenarios.
   • Unreal Engine: Select an Actor in the World Outliner during PIE (Play In Editor). The Details panel allows you to inspect and modify properties.

5. Unreal Engine Crash Reporter

   • Purpose: Provides a detailed report with a call stack and relevant information when an Unreal game crashes.
   • Technique: When “An Unreal Process Has Crashed” appears, the crash reporter will launch. Always submit the report (if prompted) and copy the call stack and log output. This information is critical for pinpointing the crash location, especially if you have debug symbols installed.

Advanced Debugger Setup

For deep-seated crashes, especially those involving engine code or complex interactions, a robust debugger setup is essential.

Attaching Visual Studio to Game Processes

When to use: When the game crashes outside the editor, or when you need to debug engine source code.

1. Prepare your game for debugging:
   • Unity: Build your game with the “Development Build” option checked and “Script Debugging” enabled. This includes debug symbols and allows the debugger to attach.
   • Unreal Engine: Build your game with a DebugGame or Development configuration. For Unreal Engine 5.7.1, debugging works well. Ensure you have the engine source code and debug symbols.
     • Linux builds (UE 5.4.1+): Ensure your DebugGame build correctly packages all necessary plugins and shared libraries. Issues like “cannot find plugins” can prevent the debugger from attaching or the game from even launching. You might need to manually verify ldd output for your executable.
2. Launch the game executable.
3. Attach Visual Studio 2026 Community:
   • Open Visual Studio.
   • Go to Debug > Attach to Process... (or press Ctrl+Alt+P).
   • In the “Attach to Process” dialog, ensure “Attach to:” is set to Automatic: Managed (.NET 5+, .NET Core) code for Unity C# projects, or Automatic: Native code for Unreal C++ projects. For Unity, sometimes Managed (v4.0, v3.5, v2.0) is needed for older runtimes, but for Unity 6.x, .NET 5+ is typical.
   • Find your game’s executable process (e.g., MyGame.exe for Unity, UE4Editor.exe or MyGame.exe for Unreal) in the list and click Attach.
   • Verification: Visual Studio’s status bar will indicate “Ready (Debugging)”. You should now be able to hit breakpoints in your game code.

Loading Debug Symbols

When to use: To get meaningful call stacks and inspect variables in engine code, not just your game code.

1. Ensure Symbols are Available:
   • Unity: Development builds with “Script Debugging” include PDB files for your managed code. For engine symbols, you might need to download specific Unity Editor debug packages.
   • Unreal Engine: When building Unreal Engine from source, ensure you build the DebugGame or Development configuration with debug symbols. For binary engine versions, you can download debug symbols via the Epic Games Launcher (under “Engine Versions” -> “Options” -> “Debug Symbols”). These symbols (PDB files on Windows, DWARF on Linux) allow the debugger to map memory addresses to source code lines.
   • Linux specific: For UE 5.4.1+ on Linux, ensure debug symbols are correctly installed for the compiled engine. The Search Evidence notes that “Debug symbols allow you to get a correct callstack for engine code.”
2. Configure Visual Studio Symbol Settings:
   • Go to Debug > Options... > Debugging > Symbols.
   • Add the path to your Unreal Engine’s Engine/Binaries/Symbols directory (or where Unity’s debug packages are extracted).
   • You can also configure Microsoft Symbol Servers for system DLLs.
   • Verification: After attaching to the process, check the “Modules” window (Debug > Windows > Modules). Look for your game’s DLLs and the engine DLLs. Their “Symbol Status” should indicate “Symbols loaded.” If it says “No symbols loaded,” right-click the module and select “Load Symbols.”

Configuring Just-In-Time (JIT) Debugging

When to use: To automatically attach a debugger when an unhandled exception occurs in your game.

1. Windows JIT Debugging:
   • Ensure Visual Studio 2026 Community is set as the default JIT debugger.
   • Go to Debug > Options... > Debugging > Just-In-Time.
   • Make sure “Managed,” “Native,” and “Script” checkboxes are enabled.
   • Verification: If your game crashes with an unhandled exception, Windows should prompt you to debug the process with Visual Studio.

Solution: System & Environment Optimization

When to use: When crash symptoms suggest hardware instability, driver conflicts, or general system unreliability (e.g., screen lock-ups, buzzing, BSODs, intermittent crashes across multiple games).

1. Update Graphics Drivers

• Trigger Condition: Any crash, especially with visual artifacts, or if drivers haven’t been updated recently.
• Action:
  1. Clean Uninstall: Use Display Driver Uninstaller (DDU) in Windows Safe Mode to completely remove existing drivers. This prevents conflicts.
  2. Download Latest: Visit the official website for your GPU manufacturer (NVIDIA, AMD, Intel) and download the latest stable driver package for your specific GPU model and OS version.
  3. Install: Perform a clean installation of the new drivers.
• Verification: Run the game. Monitor for crashes. Check GPU temperatures with tools like MSI Afterburner or HWMonitor.

2. Disable Virtualization Features

• Trigger Condition: Crashes specifically in Unity games (as noted in Search Evidence), or if you have Hyper-V, WSL, or other virtualization software installed.
• Action (Windows):
  1. Open “Turn Windows features on or off” (search in Start Menu).
  2. Uncheck Hyper-V, Virtual Machine Platform, and Windows Subsystem for Linux.
  3. Restart your PC.
• Verification: Run the game. If the crashes were related to virtualization, they should cease. You might need to re-enable these features if you require them for development.

3. Monitor Hardware & Check PSU

• Trigger Condition: Screen lock-ups, buzzing sounds, sudden PC shutdowns, or crashes that occur under heavy load after some playtime. The Search Evidence points to PSU failure for Unity crashes.
• Action:
  1. Monitor Temperatures: Use tools like HWMonitor, MSI Afterburner, or GPU-Z to monitor CPU and GPU temperatures while playing the game. High temperatures (e.g., GPU > 85°C, CPU > 90°C) indicate overheating.
  2. Check PSU: If you suspect PSU failure, the most reliable test is to swap it with a known good, adequately powerful PSU. Alternatively, use a PSU tester if available. Ensure your PSU wattage meets or exceeds the recommended wattage for your GPU and CPU combination.
  3. Underclock/Under-volt (GPU): As a diagnostic step, slightly underclocking or under-volting your GPU using tools like MSI Afterburner can reduce power draw and heat, potentially stabilizing a system with a weak PSU or overheating GPU.
• Verification: If temperatures are stable and crashes persist, the PSU might be the culprit. If swapping the PSU resolves the issue, you’ve found the root cause.

4. Verify Game Files

• Trigger Condition: Crashes on startup or during specific loading sequences, especially after a fresh install or update.
• Action (Steam/Epic Games Launcher):
  1. Steam: Right-click the game in your Library -> Properties -> Installed Files -> Verify integrity of game files....
  2. Epic Games Launcher: Go to your Library -> Click the three dots next to the game -> Manage -> Verify Files.
• Verification: The launcher will redownload any corrupted or missing files. Run the game.

Solution: Utilizing In-Engine Debugging Features (Unreal Engine)

When to use: When you suspect the crash originates from within Unreal Engine’s runtime behavior, asset loading, or specific game logic, and you need more context than a simple crash report.

1. Analyzing the Unreal Engine Crash Reporter

• Trigger Condition: Any time “An Unreal Process Has Crashed” dialog appears.
• Action:
  1. When the crash reporter appears, do not close it immediately.
  2. Click “Show Callstack” or “View Log” to expand the details.
  3. Copy the entire call stack and the last few hundred lines of the log output.
  4. Paste this information into a text file or your issue tracker.
  5. The call stack will often point directly to the function where the crash occurred. Look for functions from your game module first.
• Verification: The copied call stack and logs provide the primary evidence for further debugging in Visual Studio.

2. Using Unreal Engine Console Commands

• Trigger Condition: To inspect runtime state, toggle debug visuals, or teleport around the map without recompiling.
• Action:
  1. During Play In Editor (PIE) or in a Development build, press ~ (tilde) to open the console.
  2. Common Commands:
     • stat fps: Displays frames per second.
     • stat unit: Displays frame time for game, draw, GPU, and RHI.
     • stat memory: Shows memory usage.
     • obj list: Lists all UObjects currently loaded. Useful for finding unexpected objects or memory leaks.
     • debug crash: Forces a crash. Useful for testing crash reporter setup.
     • debug fatal: Forces a fatal error.
     • r.ScreenPercentage 50: Lowers rendering resolution (useful for performance-related crashes).
     • FreezeRendering: Freezes the rendering thread, useful for isolating game thread issues.
     • Teleport [X] [Y] [Z]: Teleports the player to specific coordinates. The Search Evidence mentions pairing this with a debug camera.
     • ToggleDebugCamera: Switches to a free-flying debug camera.
     • Show Collision: Visualizes collision meshes.
     • Show Navigation: Visualizes navigation meshes.
• Verification: Observe the effects of the commands directly in the game window or the output log. For crashes, these commands help narrow down the context.

3. Blueprint Debugging

• Trigger Condition: Crashes or unexpected behavior originating from Blueprint logic.
• Action:
  1. Open the Blueprint you suspect.
  2. Set breakpoints on specific nodes by right-clicking them and selecting Toggle Breakpoint.
  3. Start PIE. When execution hits a breakpoint, the editor will pause, and the Blueprint graph will highlight the active path.
  4. Use the “Call Stack” and “Watch” windows within the Blueprint debugger to inspect variable values and execution flow.
• Verification: Stepping through the Blueprint allows you to visually confirm the logic flow and identify where unexpected values or None references might be occurring.

Best Practices for Stable Game Code

Preventing crashes is always better than debugging them. Adopting these best practices will significantly improve the stability of your Unity and Unreal Engine games.

1. Defensive Programming:
   • Always check for nulls/nullptr: Before accessing any object or pointer, verify it’s valid.
     • Unity (C#): if (myObject != null)
     • Unreal (C++): if (MyPointer) { ... } or if (IsValid(MyActorPointer))
   • Validate input: Ensure function arguments are within expected ranges.
   • Handle edge cases: Consider empty lists, zero divisions, and out-of-bounds array access.
   • Use ensure (Unreal) or Debug.Assert (Unity): These macros/methods can catch assumptions that are violated and log errors without necessarily crashing the game in development builds.
2. Consistent Logging:
   • Use Debug.Log/UE_LOG not just for debugging, but to track important events, state changes, and potential error conditions in your game.
   • Implement different log levels (Info, Warning, Error, Fatal) and use them appropriately.
   • Ensure logs are accessible in shipped builds (e.g., written to a file) for post-mortem analysis.
3. Regular Code Reviews:
   • Have other developers review your code. A fresh pair of eyes can spot logical errors, potential null references, or inefficient patterns that could lead to crashes.
4. Performance Profiling:
   • Regularly use Unity’s Profiler or Unreal’s Profiler (e.g., stat startfile/stat stopfile and Unreal Insights) to identify performance bottlenecks, memory spikes, and unexpected CPU/GPU usage. Performance issues can sometimes lead to crashes, especially on lower-end hardware.
5. Version Control & Branching:
   • Use robust version control (Git, Perforce, Unity Version Control/Plastic SCM as mentioned in Search Evidence) to track all code and asset changes. This allows you to easily revert to a stable state if a new commit introduces a crash.
   • Utilize feature branches to isolate new development, preventing unstable code from affecting the main development line.
6. Automated Testing:
   • Implement unit tests for critical game logic and integration tests for core systems. Automated tests can catch regressions and prevent crashes from being introduced by new code.

Quick Diagnostic Checklist

When a game crashes, run through this checklist for initial diagnostics before diving deep.

• Restart the PC: A simple restart can resolve temporary OS or driver glitches.
• Check for latest Graphics Drivers: Are your GPU drivers up to date? (NVIDIA, AMD, Intel)
• Verify Game Files: Use Steam/Epic Games Launcher’s “Verify” feature.
• Disable Background Apps: Close overlays (Discord, Steam), antivirus, and other resource-intensive software.
• Monitor Temperatures: Are CPU/GPU temperatures within safe limits (under 85-90°C)?
• Check for Virtualization: Do you have Hyper-V, WSL, or other VMs enabled? Try disabling them.
• Review Crash Log/Reporter: For Unreal, copy the full crash report. For Unity, check the Editor.log or player log (_Data/output_log.txt).
• Reproduce the Crash: Can you reliably make the crash happen? If so, what are the exact steps?
• Test on Different Hardware/OS: Does the crash occur on another machine or a different OS version (if applicable, e.g., Linux vs. Windows)?

Related Errors You Might Encounter

1. Out of Memory: Often precedes a crash, indicating the game tried to allocate more RAM than available. Can be caused by memory leaks, excessive asset loading, or insufficient system RAM.
2. Shader Compilation Failed: Indicates an issue with your graphics driver, the GPU’s capabilities, or a malformed shader in your project. Often prevents the game from starting or causes rendering artifacts.
3. Assertion Failed: Common in Unreal Engine, this indicates a programmer’s assumption about the state of the program was violated. It’s often a deliberate crash in development builds to highlight a bug.