Crash/Freeze Fortnite

Unreal Engine FMallocBinned2 Crash on Inventory Open/Death - Fortnite Mac Fix Guide

📅 Published: 2026-02-06 🔄 Updated: 2026-02-06 👥 Reports: 12 ⚡ Severity: 🟢 Low

🎯 Quick Answer

Clear the Fortnite cache and verify game files through the Epic Games Launcher to resolve the memory allocation corruption causing the FMallocBinned2 crash.

SECTION 1: OVERVIEW

The error is a fatal memory allocation failure within the Unreal Engine 4 runtime. The specific technical fault is an FMallocBinned2 allocator detecting a corrupted memory block canary value during a reallocation operation. The allocator expects a canary value of 0xe3 but finds 0x3f, indicating heap memory corruption has occurred prior to the crash. This problem manifests exclusively on the macOS platform, affecting the Fortnite Battle Royale client. The issue is documented in game versions following the v3.5 update. This is a common occurrence for affected systems, with a high severity impact as it results in an immediate and unrecoverable application termination. The exact error message is:

Fatal error: [File:Unknown] [Line: 1146] FMallocBinned2 Attempt to realloc an unrecognized block 0x700009160000 canary == 0x3f != 0xe3

SECTION 2: SYMPTOMS

The FortniteClient-Mac-Shipping process terminates unexpectedly during specific in-game events. The application displays an Unreal Engine crash reporter dialog with the FMallocBinned2 error. The crash occurs with precise triggers: when the player opens the inventory screen (Tab key) or at the moment of player elimination. The system generates a crash log containing the memory address of the corrupted block and a stack trace from within the FortniteClient-Mac-Shipping binary. No other warning or performance degradation precedes the immediate crash.

SECTION 3: COMMON CAUSES

Category: Game Bug / Memory Corruption Specific technical explanation: A code defect introduced in a game update (post v3.5) leads to improper memory management. This can involve a dangling pointer, a buffer overrun, or a double-free within game systems related to inventory or player state management, corrupting the allocator's metadata. Why this causes the problem: The FMallocBinned2 allocator uses canary values to guard against memory corruption. Invalid operations overwrite this canary, causing the allocator to fail on subsequent block validation. Category: Software Conflict / Cached Data Corruption Specific technical explanation: Corrupted local game cache or shader files contain invalid data structures. When the game loads these assets during inventory rendering or death sequence, it attempts to reference or modify memory using corrupted pointers. Why this causes the problem: The game engine interprets bad cache data as valid instructions, leading to memory accesses outside allocated blocks and corrupting the heap. Category: Configuration Error / Graphics API Conflict Specific technical explanation: Incompatibility between the game's rendering settings (e.g., specific effects tied to the inventory screen) and the macOS Metal graphics driver implementation. This can cause GPU memory operations to incorrectly affect system RAM. Why this causes the problem: Asynchronous texture loading or rendering during the specified UI events triggers a faulty memory path. Category: Hardware Issue / Insufficient System RAM Specific technical explanation: The system operates with minimal free RAM. Intensive operations like opening the inventory (which loads numerous item icons and models) force aggressive memory reallocation and paging. Why this causes the problem: Memory pressure exacerbates latent bugs in the game's memory management, making corruption and allocator failure more likely. Category: Software Conflict / macOS System Integrity Protection (SIP) or Sandboxing Specific technical explanation: The game client attempts to write to a protected memory region or perform an operation restricted by macOS security policies, leading to an access violation that manifests as heap corruption. Why this causes the problem: The failed operation leaves the heap in an inconsistent state, which is later detected by the allocator.

SECTION 4: SOLUTIONS

Solution 1: Clear Game Cache and Verify Files

Difficulty: Easy Time Required: 10-15 minutes Success Rate: High Prerequisites: Epic Games Launcher installed. Steps:

Completely exit the Fortnite client and the Epic Games Launcher.
Open Finder and navigate to the local cache directory. Press Cmd+Shift+G and enter ~/Library/Caches/.
Locate and move the following folders to the Trash:

- com.epicgames.EpicGamesLauncher - Fortnite

Navigate to the Application Support directory. Press Cmd+Shift+G and enter ~/Library/Application Support/.
Locate and move the Epic Games folder to the Trash.
Empty the Trash.
Restart your Mac.
Launch the Epic Games Launcher. Navigate to your Library.
Click the three dots (...) under Fortnite and select Manage.
Click the Verify button. The launcher will download and replace any corrupted files.

Technical Explanation: This process removes corrupted cached assets and configuration files that contain invalid pointers or data structures. A fresh verification ensures all game binaries and assets are intact, eliminating the source of memory corruption. Verification: Launch Fortnite and enter a match. Open the inventory multiple times (Tab key) and intentionally get eliminated. The game client remains stable without the Unreal Engine crash dialog.

Solution 2: Perform a Clean Reinstall of Fortnite

Difficulty: Medium Time Required: 30-45 minutes Success Rate: High Prerequisites: Stable internet connection for re-download. Steps:

Open the Epic Games Launcher. Navigate to your Library.
Click the three dots (...) under Fortnite and select Uninstall. Confirm the action.
Follow the steps in Solution 1 to clear all cache and application support folders (~/Library/Caches/ and ~/Library/Application Support/Epic Games).
Press Cmd+Shift+G in Finder and enter ~/Library/Preferences/. Locate and move any com.epicgames or com.EpicGames plist files to the Trash.
Restart your Mac.
Open the Epic Games Launcher, navigate to your Library, and click Install on Fortnite. Allow the full download and installation to complete.

Technical Explanation: A clean install removes all local game state, including deeply nested corrupted files in preferences and support directories that a simple verify may not overwrite. This ensures a pristine installation. Verification: After installation, the game generates entirely new configuration and cache files. Test the previously crashing triggers; the absence of crashes confirms a corrupt local file was the root cause.

Solution 3: Lower Graphics Settings to Minimum Preset

Difficulty: Easy Time Required: 5 minutes Success Rate: Medium Prerequisites: None. Steps:

Launch Fortnite and go to the main menu.
Open the Settings menu (gear icon).
Navigate to the Video Settings tab.
Set the Graphics Quality preset to Low.
Disable the following specific settings:

- Shadows: Off - Global Illumination: Off - Effects: Low - Post Processing: Low

Set View Distance to Near.
Apply the settings and restart the game when prompted.

Technical Explanation: Reducing graphics quality decreases memory allocation pressure, particularly for texture and effect loading during the inventory screen. This can circumvent the bug by preventing the engine from hitting the specific, faulty memory allocation path. Verification: The game operates with reduced visual fidelity. Monitor stability when opening the inventory and upon death; the crash frequency should reduce or cease.

Solution 4: Create a New macOS User Account for Gaming

Difficulty: Medium Time Required: 15 minutes Success Rate: Medium Prerequisites: Administrator privileges on your Mac. Steps:

Open System Preferences > Users & Groups.
Click the lock icon to make changes and enter your administrator password.
Click the + (plus) button to add a new user.
Set New Account to Administrator. Fill in the full name, account name, and password.
Click Create User.
Log out of your current account and log into the newly created account.
Download and install the Epic Games Launcher from the official website within this new user account.
Install and launch Fortnite from this new environment.

Technical Explanation: This isolates the game from any system-level configuration conflicts, corrupted user-specific caches, or permission issues in your primary user account. The new account provides a clean slate for game operation. Verification: If the crash does not occur in the new user account, the issue is isolated to corrupted files or settings within your original user's library folder.

Solution 5: Monitor and Limit Background Applications

Difficulty: Easy Time Required: 5 minutes Success Rate: Low Prerequisites: None. Steps:

Before launching Fortnite, close all non-essential applications. This includes web browsers (especially those with multiple tabs), communication apps (Discord, Slack), and other resource-intensive software.
Open Activity Monitor (located in /Applications/Utilities/).
Click the Memory tab. Observe the Memory Pressure graph at the bottom.
Ensure the graph is green and not yellow or red before launching the game.
Launch Fortnite and test the crash triggers.

Technical Explanation: Maximizing available system RAM reduces memory pressure, minimizing the chance that the game's memory corruption bug will be triggered during aggressive allocation/reallocation sequences. Verification: Activity Monitor shows high free memory and low memory pressure. Game stability during inventory operations improves.

SECTION 5: PREVENTION

Maintain a regular schedule for clearing the Fortnite cache located in ~/Library/Caches/ after every major game update. Always use the Verify function in the Epic Games Launcher following client patches. Keep macOS updated to the latest stable version to ensure graphics driver compatibility. Monitor system memory usage via Activity Monitor and ensure a minimum of 4GB of free RAM is available before launching the game. Avoid modifying game configuration files manually unless following a documented, official procedure.

SECTION 6: WHEN TO CONTACT SUPPORT

Contact Epic Games Support if all solutions fail and the FMallocBinned2 error persists across a clean macOS install on supported hardware. Provide the full crash log, which is saved to ~/Library/Logs/DiagnosticReports/FortniteClient-Mac-Shipping_.crash. Include your system specifications: macOS version, exact Mac model, and GPU details. Official support channels are accessible via the Epic Games website under the Help section. Do not contact support before completing the clean reinstall procedure outlined in Solution 2.