The app crashes after opening FAB.

General Issues & Bug Reporting (Fab)
1

Summary

LoginId:c6a96dcc4097c5a004c8598b7cd32019
EpicAccountId:43f491152d974ffd8dfab8ef2d8a60f2

Assertion failed: IsValid() [File:D:\build++UE5\Sync\LocalInstall\Engine\Source\Runtime\Core\Public\Templates\SharedPointer.h] [Line: 1071]

UnrealEditor_Core
UnrealEditor_Fab!FFabBrowser::OpenTab() [D:\build++UE5\Sync\LocalBuilds\Fab\0.0.5\HostProject\Plugins\Fab\Source\Fab\Private\FabBrowser.cpp:275]
UnrealEditor_Fab!TBaseStaticDelegateInstance<TSharedRef<SDockTab,1> __cdecl(FSpawnTabArgs const &),FDefaultDelegateUserPolicy>::Execute() [D:\build++UE5\Sync\LocalInstall\Engine\Source\Runtime\Core\Public\Delegates\DelegateInstancesImpl.h:791]
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UnrealEditor_Fab!FFabBrowser::SetupEntryPoints'::2’::<lambda_1>::operator()() [D:\build++UE5\Sync\LocalBuilds\Fab\0.0.5\HostProject\Plugins\Fab\Source\Fab\Private\FabBrowser.cpp:107]
UnrealEditor_Fab!TBaseFunctorDelegateInstance<void __cdecl(void),FDefaultDelegateUserPolicy,FFabBrowser::SetupEntryPoints'::2’::<lambda_1> >::ExecuteIfSafe() [D:\build++UE5\Sync\LocalInstall\Engine\Source\Runtime\Core\Public\Delegates\DelegateInstancesImpl.h:894] UnrealEditor_Slate UnrealEditor_Slate UnrealEditor_Slate UnrealEditor_Slate UnrealEditor_Slate UnrealEditor_Slate UnrealEditor_Slate UnrealEditor_Slate UnrealEditor_Slate UnrealEditor_Slate UnrealEditor_ApplicationCore UnrealEditor_ApplicationCore UnrealEditor_ApplicationCore UnrealEditor_ApplicationCore user32 user32 UnrealEditor_ApplicationCore UnrealEditor UnrealEditor UnrealEditor UnrealEditor UnrealEditor UnrealEditor kernel32 ntdll

What type of bug are you experiencing?

Documentation

Steps to Reproduce

The app crashes after opening FAB.

Expected Result

The app crashes after opening FAB.

Observed Result

The app crashes after opening FAB.

Platform

win 11

Operating System

win 11

2

Hi @l235711,

This crash appears to be due to a null or invalid pointer- a bug within the Cpp code of the plugin and one which you probably won’t be able to get around.

Looking at your log, it looks like you are using Fab version 0.0.5. I would try either upgrading or downgrading your plugin version and seeing if that solves your issue.

3

up!!! same for me

4

same here
LoginId:5f2881a8462e982af40bda82aaeac7c3
EpicAccountId:476f19944ecb4a8284c161da2d27972b

Assertion failed: IsValid() [File:D:\build++UE5\Sync\LocalInstall\Engine\Source\Runtime\Core\Public\Templates\SharedPointer.h] [Line: 1071]

UnrealEditor_Core
UnrealEditor_Fab!FFabBrowser::OpenTab() [D:\build++UE5\Sync\LocalBuilds\Fab\0.0.5\HostProject\Plugins\Fab\Source\Fab\Private\FabBrowser.cpp:275]
UnrealEditor_Fab!TBaseStaticDelegateInstance<TSharedRef<SDockTab,1> __cdecl(FSpawnTabArgs const &),FDefaultDelegateUserPolicy>::Execute() [D:\build++UE5\Sync\LocalInstall\Engine\Source\Runtime\Core\Public\Delegates\DelegateInstancesImpl.h:791]
UnrealEditor_Slate
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UnrealEditor_Slate
UnrealEditor_Slate
UnrealEditor_Fab!FFabBrowser::SetupEntryPoints'::2’::<lambda_1>::operator()() [D:\build++UE5\Sync\LocalBuilds\Fab\0.0.5\HostProject\Plugins\Fab\Source\Fab\Private\FabBrowser.cpp:107]
UnrealEditor_Fab!TBaseFunctorDelegateInstance<void __cdecl(void),FDefaultDelegateUserPolicy,FFabBrowser::SetupEntryPoints'::2’::<lambda_1> >::ExecuteIfSafe() [D:\build++UE5\Sync\LocalInstall\Engine\Source\Runtime\Core\Public\Delegates\DelegateInstancesImpl.h:894]
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UnrealEditor_ApplicationCore
UnrealEditor_ApplicationCore
UnrealEditor_ApplicationCore
UnrealEditor_ApplicationCore
user32
user32
UnrealEditor_ApplicationCore
UnrealEditor
UnrealEditor
UnrealEditor
UnrealEditor
UnrealEditor
UnrealEditor
kernel32
ntdll

5

Thx for the tip, but how can I change FAb version?

6

Hello everyone,

After extensive troubleshooting, I have found the definitive solution for this Fab plugin crash.

The root cause is a specific incompatibility in UE 5.6 between the Fab plugin and projects that have non-ASCII names.

Here is the precise breakdown:

  1. Normal UE Behavior: In general, creating and using a UE project with a Chinese name does not cause a crash.

  2. The Crash Trigger: The crash only occurs under this specific condition:

    • You are using Unreal Engine 5.6.

    • You are trying to use the Fab plugin.

    • Your project name (.uproject file and its parent folder) contains non-ASCII characters (like Chinese).

    When these three conditions are met, the editor will crash. I have not tested this on other versions of Unreal Engine yet.

  3. Path vs. Name Distinction Still Applies: My previous finding that the folder path can contain Chinese characters is still correct. The issue is strictly with the project name itself.

    • This will CRASH (in UE 5.6 when using Fab):

      D:\我的UE工程\今宵月.uproject

      (Project name “今宵月” is non-ASCII.)

    • This works correctly (in UE 5.6 when using Fab):

      D:\我的UE工程\MyProject.uproject

      (Project name “MyProject” is ASCII, even though the path is not.)

Solution / TL;DR: If you are using UE 5.6 and experiencing crashes related to the Fab plugin, the immediate workaround is to rename your project folder and .uproject file to use only English characters.

This is definitely a bug within the Fab plugin’s implementation in UE 5.6. Hopefully, the Epic team can fix its handling of Unicode project names.

Thank you, and I hope this clarification helps everyone!