Unreal Engine Issues and Bug Tracker (UE-49739)

Description

After deriving a C++ class from another class and then closing the editor, the project will crash when reopened. This crash will continue until the project files are regenerated and the project is rebuilt in Xcode.

NOTE: 16.59.47 log is the C++ class being added, 17.13.07 log is the actual crash

This issue does NOT occur on Windows.

This issue also occurs in 4.17.1 and Main.

Workaround

After closing the editor, navigate to the location of the project and find the .uproject file.
Right click on the .uproject file and select Services > Generate Xcode Project from the context menu
Open the .xcworkspace file and build the project scheme again
The editor should now be able to open the project successfully and will still have the new C++ class in the Content Browser.

Steps to Reproduce

Open QAGame in UE4 on Mac
Click on the folder icon next to Content in the top bar of the Content Browser
Scroll down to the bottom of the drop-down menu and navigate to C++ Classes > QAGame > Classes
Double click the Classes folder to bring it up in the Content Browser
Right click on QADeriveTest and select Create C++ class derived from QADeriveTest
Name the class as you please and click Create Class
Allow the editor to compile the new class and then confirm it appears in the Content Browser
Close the editor and then reopen the project

Expected Result
Project reopens cleanly and successfully without crashing

Actual Result
Project crashes during opening

Callstack

UE4Editor-CoreUObject.dylib!UClassCompiledInDefer() 
UE4Editor-QAGame.dylib!<Unknown> 
???!Unknown() 
???!Unknown() 
???!Unknown() 
???!Unknown() 
???!Unknown() 
???!Unknown() 
???!Unknown() 
???!Unknown() 
libdyld.dylib!<Unknown> 
UE4Editor-Core.dylib!FMacPlatformProcess::GetDllHandle() 
UE4Editor-Core.dylib!FModuleManager::LoadModuleWithFailureReason() 
UE4Editor-Projects.dylib!FModuleDescriptor::LoadModulesForPhase() 
UE4Editor-Projects.dylib!FProjectManager::LoadModulesForProject() 
UE4Editor!FEngineLoop::LoadStartupModules() 
UE4Editor!FEngineLoop::PreInit() 
UE4Editor!GuardedMain() 
UE4Editor!<Unknown> 
UE4Editor-Core.dylib!<Unknown> 
Foundation!Unknown() 
libsystem_pthread.dylib!<Unknown> 
libsystem_pthread.dylib!<Unknown> 
libsystem_pthread.dylib!<Unknown>

Community References

UE-50753 to fix UE-49739. Mac Only issue slows down windows flow?

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Fixed

Component	UE - Foundation - Cpp Tools - Hot Reload
Affects Versions	4.17.1, 4.17.2, 4.18
Target Fix	4.18

Fix Commit	3658442
Main Commit	3661409
Release Commit	3658442

Created	Sep 13, 2017
Resolved	Sep 22, 2017
Updated	Apr 27, 2018

UE-49739

Editor Crashes on Opening After Deriving C++ Class from Another Class

Editor Crashes on Opening After Deriving C++ Class from Another Class

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