Unreal Engine Issues

UE-93845

Crash when setting a module input to read from a new user parameter

Crash when setting a module input to read from a new user parameter

Description

Crash when setting a module input to read from a new user parameter

Crash does not occur when drag/dropping a User Parameter from the Parameters panel into the input, or when selecting a preexisting user param. 

This does NOT happen at 4.25.0's CL 13144385.

Steps to Reproduce

Setting an input to a new Parameter:

  1. Open a project
  2. Create and open a Niagara System based on the Fountain emitter
  3. Select the Scale Color module
  4. Click the "edit input" option to the right of Scale Curve
  5. Search for and select Read from new User parameter

Copy/Pasting an Emitter with a User Parameter input into another System:

  1. Open a project
  2. Create and open a Niagara System based on the Fountain emitter
  3. In the Parameters panel, create a new User Float parameter
  4. Drag/Drop the parameter into Scale Color's Scale Curve input
  5. Copy the Emitter
  6. Open another System
  7. Paste the Emitter into the System

Result: Editor crashes

Callstack
Assertion failed: (Index >= 0) & (Index < ArrayNum) [File:D:\Build\++UE4+Licensee\Sync\Engine\Source\Runtime\Core\Public\Containers/Array.h] [Line: 674] Array index out of bounds: 0 from an array of size 0

UE4Editor_Core!AssertFailedImplV() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Runtime\Core\Private\Misc\AssertionMacros.cpp:100]
UE4Editor_Core!FDebug::CheckVerifyFailedImpl() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Runtime\Core\Private\Misc\AssertionMacros.cpp:450]
UE4Editor_Niagara!DispatchCheckVerify<void,<lambda_eba3ce5784d25af8de3c4fae4e261050> >() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Runtime\Core\Public\Misc\AssertionMacros.h:162]
UE4Editor_Niagara!UNiagaraSystem::RequestCompile() [D:\Build\++UE4+Licensee\Sync\Engine\Plugins\FX\Niagara\Source\Niagara\Private\NiagaraSystem.cpp:1312]
UE4Editor_NiagaraEditor!FNiagaraSystemViewModel::CompileSystem() [D:\Build\++UE4+Licensee\Sync\Engine\Plugins\FX\Niagara\Source\NiagaraEditor\Private\ViewModels\NiagaraSystemViewModel.cpp:259]
UE4Editor_NiagaraEditor!FNiagaraSystemViewModel::Tick() [D:\Build\++UE4+Licensee\Sync\Engine\Plugins\FX\Niagara\Source\NiagaraEditor\Private\ViewModels\NiagaraSystemViewModel.cpp:586]
UE4Editor_UnrealEd!FTickableEditorObject::TickObjects() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Editor\UnrealEd\Public\TickableEditorObject.h:45]
UE4Editor_UnrealEd!UEditorEngine::Tick() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Editor\UnrealEd\Private\EditorEngine.cpp:1480]
UE4Editor_UnrealEd!UUnrealEdEngine::Tick() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Editor\UnrealEd\Private\UnrealEdEngine.cpp:414]
UE4Editor!FEngineLoop::Tick() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Runtime\Launch\Private\LaunchEngineLoop.cpp:4850]
UE4Editor!GuardedMain() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Runtime\Launch\Private\Launch.cpp:169]
UE4Editor!GuardedMainWrapper() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Runtime\Launch\Private\Windows\LaunchWindows.cpp:137]
UE4Editor!WinMain() [D:\Build\++UE4+Licensee\Sync\Engine\Source\Runtime\Launch\Private\Windows\LaunchWindows.cpp:268]
UE4Editor!__scrt_common_main_seh() [d:\agent\_work\5\s\src\vctools\crt\vcstartup\src\startup\exe_common.inl:288]
kernel32
ntdll

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Fixed
ComponentUE - Niagara
Affects Versions4.25, 4.25.1, 4.26
Target Fix4.25.2
Fix Commit13614415
Main Commit14151001
Release Commit13614415
CreatedJun 2, 2020
ResolvedJun 8, 2020
UpdatedJan 12, 2021
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