# Hot Reload crashes Editor **URL:** \ **Category:** Getting Started & Setup\ **Tags:** crashes, unreal-engine, UE4-25, crash, Visual-Studio, question, hot-reload\ **Created:** [May 21, 2020, 8:59am UTC](https://forums.unrealengine.com/t/hot-reload-crashes-editor/465443 "2020-05-21T08:59:25Z")\ **Posts on this page:** 11\ **Page:** 1
**Author:** ![AndrewVal](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@AndrewVal](https://forums.unrealengine.com/u/AndrewVal)\ **Post date:** [May 21, 2020, 8:59am UTC](https://forums.unrealengine.com/t/hot-reload-crashes-editor/465443/1 "2020-05-21T08:59:25Z")
Since 4.25 HotReload doesn’t work properly. Everytime when I compile a project in Visual Studio or inside UE4 Editor I’ve got a crash with the following CallStack and Exception _Unhandled exception at 0x00007FF9AC0F0DA8 (UE4Editor-CoreUObject.dll) in UE4Minidump.dmp: 0xC0000005: Access violation reading location 0xFFFFFFFFFFFFFFFF. occurred_ > [Inline Frame] UE4Editor-CoreUObject.dll!FField::HasAnyCastFlags(const unsigned \_\_int64) Line 499 C++ > [Inline Frame] UE4Editor-CoreUObject.dll!CastField(FField \*) Line 796 C++ > [Inline Frame] UE4Editor-CoreUObject.dll!TFieldPath::{ctor}(FField \* InProperty, TFieldPath::EDummy1) Line 325 C++ > UE4Editor-CoreUObject.dll!FPropertyProxyArchive::operator\<\<(FField \* & Value) Line 45 C++ > [Inline Frame] UE4Editor-CoreUObject.dll!operator\<\<(FArchive &) Line 93 C++ > UE4Editor-CoreUObject.dll!UStruct::SerializeExpr(int & iCode, FArchive & Ar) Line 222 C++ > UE4Editor-CoreUObject.dll!UStruct::SerializeExpr(int & iCode, FArchive & Ar) Line 314 C++ > UE4Editor-CoreUObject.dll!UStruct::Serialize(FArchive & Ar) Line 1925 C++ > UE4Editor-CoreUObject.dll!UFunction::Serialize(FArchive & Ar) Line 5555 C++ > [Inline Frame] UE4Editor-HotReload.dll!FHotReloadModule::ReplaceReferencesToReconstructedCDOs::\_\_l2::FFindRefTask::DoWork() Line 983 C++ > UE4Editor-HotReload.dll!FAsyncTask\<`FHotReloadModule::ReplaceReferencesToReconstructedCDOs'::`2’::FFindRefTask\>::DoWork() Line 271 C++ > UE4Editor-HotReload.dll!FAsyncTask\<`FHotReloadModule::ReplaceReferencesToReconstructedCDOs'::`2’::FFindRefTask\>::DoThreadedWork() Line 296 C++ > UE4Editor-Core.dll!FQueuedThread::Run() Line 855 C++ > UE4Editor-Core.dll!FRunnableThreadWin::Run() Line 86 C++ > UE4Editor-Core.dll!FRunnableThreadWin::GuardedRun() Line 35 C++ ---
**Author:** ![Prashast](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Prashast](https://forums.unrealengine.com/u/Prashast)\ **Post date:** [June 17, 2020, 10:38pm UTC](https://forums.unrealengine.com/t/hot-reload-crashes-editor/465443/2 "2020-06-17T22:38:39Z")
I am getting the same error since upgrading to 4.25.1 with the same call stack. If you want to try to troubleshoot this with me here’s my company Discord: [PARIAH](https://discord.gg/SXGJmpQ) ---
**Author:** ![ClockworkOcean](https://d1ap1mz92jnks1.cloudfront.net/user_avatar/forums.unrealengine.com/clockworkocean/32/1169999_2.png) [@ClockworkOcean](https://forums.unrealengine.com/u/ClockworkOcean)\ **Post date:** [June 19, 2020, 8:54am UTC](https://forums.unrealengine.com/t/hot-reload-crashes-editor/465443/3 "2020-06-19T08:54:56Z")
Did you get anywhere with this? I’m getting the same crash, 4.25, when compiling blueprints in editor… ---
**Author:** ![Squeaky-Bed](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Squeaky-Bed](https://forums.unrealengine.com/u/Squeaky-Bed)\ **Post date:** [July 6, 2020, 2:22pm UTC](https://forums.unrealengine.com/t/hot-reload-crashes-editor/465443/4 "2020-07-06T14:22:06Z")
Same here, I am looking for an answer to this. ---
**Author:** ![MWTAHM](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@MWTAHM](https://forums.unrealengine.com/u/MWTAHM)\ **Post date:** [July 17, 2020, 6:14pm UTC](https://forums.unrealengine.com/t/hot-reload-crashes-editor/465443/5 "2020-07-17T18:14:40Z")
Same s\*\*\* here ---
**Author:** ![lyonb96](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@lyonb96](https://forums.unrealengine.com/u/lyonb96)\ **Post date:** [August 6, 2020, 7:03am UTC](https://forums.unrealengine.com/t/hot-reload-crashes-editor/465443/6 "2020-08-06T07:03:40Z")
Different callstack but same issue for me. About a third of all hot-reloads from Visual Studio crash the editor. 4.25 has been absolute hell for me, the editor crashes far more often than it did in 4.24. ---
**Author:** ![Nazruden](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Nazruden](https://forums.unrealengine.com/u/Nazruden)\ **Post date:** [August 11, 2020, 8:46am UTC](https://forums.unrealengine.com/t/hot-reload-crashes-editor/465443/7 "2020-08-11T08:46:16Z")
Exact same error for me, all the time. Don’t know what’s going on… ---
**Author:** ![bengoog](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@bengoog](https://forums.unrealengine.com/u/bengoog)\ **Post date:** [October 9, 2020, 3:18pm UTC](https://forums.unrealengine.com/t/hot-reload-crashes-editor/465443/8 "2020-10-09T15:18:37Z")
This started happening on our team when we switched to 4.25 as well. ---
**Author:** ![bengoog](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@bengoog](https://forums.unrealengine.com/u/bengoog)\ **Post date:** [October 9, 2020, 4:51pm UTC](https://forums.unrealengine.com/t/hot-reload-crashes-editor/465443/9 "2020-10-09T16:51:20Z")
For our project, this was caused by doing the following in an Actor’s constructor: ``` FSoftClassPath ClassReference = ... UClass* MyClass = ClassReference.ResolveClass(); if (!MyClass) { MyClass = ClassReference.TryLoadClass(); } ``` Protecting this code with ``` if (!HasAnyFlags(RF_ClassDefaultObject)) ``` solved the hot reloading issue. ---
**Author:** ![PatrikAutomatic](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@PatrikAutomatic](https://forums.unrealengine.com/u/PatrikAutomatic)\ **Post date:** [December 17, 2020, 7:44am UTC](https://forums.unrealengine.com/t/hot-reload-crashes-editor/465443/10 "2020-12-17T07:44:18Z")
Same issue in 4.26 ---
**Author:** ![Alakuloinen](https://d3kjluh73b9h9o.cloudfront.net/original/4X/2/8/5/28502927f1d97ba1051b3b47ccfe17233bf41ef0.png) [@Alakuloinen](https://forums.unrealengine.com/u/Alakuloinen)\ **Post date:** [April 3, 2021, 4:20pm UTC](https://forums.unrealengine.com/t/hot-reload-crashes-editor/465443/11 "2021-04-03T16:20:26Z")
The bengoog’s answer really points to the right side. I’d add a more general assumption: any complicated stuff in U- and A- classes’ constructors should be relocated to other functions or protected like in the unswer above. In my case a similar crash was caused by a TArray::SetNum() + elements initializing in a constructor. So the main problem is to keep in mind all your subclasses and go through them all.