Unreal 5.6 on Linux, Start and Crash

sbbg · June 4, 2025, 12:16pm

I just compiled a new copy of Unreal 5.6 in Linux.
In order to prevent any unusual situation, I start with a pure new 3rd person template.
But it will crash immediately with VulkanRHI. Can anyone tell me what could be wrong?
(Linux 6.14, mesa-25.1)

[2025.06.04-11.54.06:120][ 4]LogCore: === Critical error: ===
Unhandled Exception: SIGSEGV: invalid attempt to write memory at address 0x0000000000000003

[2025.06.04-11.54.06:120][ 4]LogCore: Assertion failed: !"Enclosing block should never be called" [File:./Runtime/VulkanRHI/Private/VulkanUtil.cpp] [Line: 96
5]

0x00007fd0dea346a9 libUnrealEditor-Core.so!FDebug::CheckVerifyFailedImpl2(char const*, char const*, int, char16_t const*, ...) [/home/sbbg/Shared/UE5/UE-5.6/E
ngine/Source/./Runtime/Core/Private/Misc/AssertionMacros.cpp:724]
0x00007fcf7e052481 libUnrealEditor-VulkanRHI.so!VulkanRHI::VerifyVulkanResult(VkResult, char const*, char const*, unsigned int) [/home/sbbg/Shared/UE5/UE-5.6/
Engine/Source/./Runtime/VulkanRHI/Private/VulkanUtil.cpp:965]
0x00007fcf7e05b937 libUnrealEditor-VulkanRHI.so!FVulkanSwapChain::Present(FVulkanQueue*, VulkanRHI::FSemaphore*) [/home/sbbg/Shared/UE5/UE-5.6/Engine/Source/.
/Runtime/VulkanRHI/Private/VulkanSwapChain.cpp:873]
0x00007fcf7e06e5e7 libUnrealEditor-VulkanRHI.so!FVulkanViewport::DoCheckedSwapChainJob(FVulkanCommandListContext&, TFunction<int (FVulkanViewport*)>) [/home/s
bbg/Shared/UE5/UE-5.6/Engine/Source/Runtime/Core/Public/Templates/Function.h:471]
0x00007fcf7e07461b libUnrealEditor-VulkanRHI.so!FVulkanViewport::Present(FVulkanCommandListContext&, FVulkanQueue*, bool) [/home/sbbg/Shared/UE5/UE-5.6/Engine
/Source/./Runtime/VulkanRHI/Private/VulkanViewport.cpp:1119]
0x00007fcf7e00fbec libUnrealEditor-VulkanRHI.so!FVulkanCommandListContext::RHIEndDrawingViewport(FRHIViewport*, bool, bool) [/home/sbbg/Shared/UE5/UE-5.6/Engi
ne/Source/./Runtime/VulkanRHI/Private/VulkanRHI.cpp:1273]
0x00007fd0d68700dd libUnrealEditor-RHI.so!FRHICommand<FRHICommandEndDrawingViewport, FRHICommandEndDrawingViewportString2524>::ExecuteAndDestruct(FRHICommandL
istBase&) [/home/sbbg/Shared/UE5/UE-5.6/Engine/Source/Runtime/RHI/Public/RHICommandListCommandExecutes.inl:591]
0x00007fd0d682a6ad libUnrealEditor-RHI.so!FRHICommandListBase::Execute() [/home/sbbg/Shared/UE5/UE-5.6/Engine/Source/./Runtime/RHI/Private/RHICommandList.cpp:
527]
0x00007fd0d682cfd9 libUnrealEditor-RHI.so!FRHICommandListExecutor::FTranslateState::Translate(FRHICommandListBase*) [/home/sbbg/Shared/UE5/UE-5.6/Engine/Sourc
e/./Runtime/RHI/Private/RHICommandList.cpp:1077]
0x00007fd0d6848e50 libUnrealEditor-RHI.so!UE::Core::Private::Function::TFunctionRefCaller<FRHICommandListExecutor::FSubmitState::Dispatch(FRHICommandListBase*
)::$_0, void>::Call(void*) [/home/sbbg/Shared/UE5/UE-5.6/Engine/Source/./Runtime/RHI/Private/RHICommandList.cpp:1028]
0x00007fd0d682ae85 libUnrealEditor-RHI.so!FRHICommandListExecutor::FTaskPipe::Execute(FRHICommandListExecutor::FTaskPipe::FTask*, TRefCountPtr<FBaseGraphTask>
const&) const [/home/sbbg/Shared/UE5/UE-5.6/Engine/Source/Runtime/Core/Public/Templates/Function.h:471]
0x00007fd0dee58bb5 libUnrealEditor-Core.so!TGraphTask<TFunctionGraphTaskImpl<void (ENamedThreads::Type, TRefCountPtr<FBaseGraphTask> const&), (ESubsequentsMod
e::Type)0> >::ExecuteTask() [/home/sbbg/Shared/UE5/UE-5.6/Engine/Source/Runtime/Core/Public/Templates/Function.h:471]
0x00007fd0de6e4095 libUnrealEditor-Core.so!UE::Tasks::Private::FTaskBase::TryExecuteTask() [/home/sbbg/Shared/UE5/UE-5.6/Engine/Source/Runtime/Core/Public/Tas
ks/TaskPrivate.h:527]
0x00007fd0de6e2a2d libUnrealEditor-Core.so!FNamedTaskThread::ProcessTasksNamedThread(int, bool) [/home/sbbg/Shared/UE5/UE-5.6/Engine/Source/Runtime/Core/Publi
c/Async/TaskGraphInterfaces.h:505]
0x00007fd0de6e0c6f libUnrealEditor-Core.so!FNamedTaskThread::ProcessTasksUntilQuit(int) [/home/sbbg/Shared/UE5/UE-5.6/Engine/Source/./Runtime/Core/Private/Asy
nc/TaskGraph.cpp:667]
0x00007fd0d6c599d9 libUnrealEditor-RenderCore.so!FRHIThread::Run() [/home/sbbg/Shared/UE5/UE-5.6/Engine/Source/./Runtime/RenderCore/Private/RenderingThread.cp
p:270]
0x00007fd0de8bf5a6 libUnrealEditor-Core.so!FRunnableThreadPThread::Run() [/home/sbbg/Shared/UE5/UE-5.6/Engine/Source/./Runtime/Core/Private/HAL/PThreadRunnabl
eThread.cpp:25]
0x00007fd0de811b4a libUnrealEditor-Core.so!FRunnableThreadPThread::_ThreadProc(void*) [/home/sbbg/Shared/UE5/UE-5.6/Engine/Source/Runtime/Core/Private/HAL/PTh
readRunnableThread.h:187]
0x00007fd0d1c61b1e libc.so.6!UnknownFunction(0x94b1d)
0x00007fd0d1ce4d4c libc.so.6!UnknownFunction(0x117d4b)

0x00007fd0dea346a9 libUnrealEditor-Core.so!FDebug::CheckVerifyFailedImpl2(char const*, char const*, int, char16_t const*, ...) [/home/sbbg/Shared/UE5/UE-5.6/E
ngine/Source/./Runtime/Core/Private/Misc/AssertionMacros.cpp:724]
0x00007fcf7e052481 libUnrealEditor-VulkanRHI.so!VulkanRHI::VerifyVulkanResult(VkResult, char const*, char const*, unsigned int) [/home/sbbg/Shared/UE5/UE-5.6/
Engine/Source/./Runtime/VulkanRHI/Private/VulkanUtil.cpp:965]
0x00007fcf7e05b937 libUnrealEditor-VulkanRHI.so!FVulkanSwapChain::Present(FVulkanQueue*, VulkanRHI::FSemaphore*) [/home/sbbg/Shared/UE5/UE-5.6/Engine/Source/.
/Runtime/VulkanRHI/Private/VulkanSwapChain.cpp:873]
0x00007fcf7e06e5e7 libUnrealEditor-VulkanRHI.so!FVulkanViewport::DoCheckedSwapChainJob(FVulkanCommandListContext&, TFunction<int (FVulkanViewport*)>) [/home/s
bbg/Shared/UE5/UE-5.6/Engine/Source/Runtime/Core/Public/Templates/Function.h:471]
0x00007fcf7e07461b libUnrealEditor-VulkanRHI.so!FVulkanViewport::Present(FVulkanCommandListContext&, FVulkanQueue*, bool) [/home/sbbg/Shared/UE5/UE-5.6/Engine
/Source/./Runtime/VulkanRHI/Private/VulkanViewport.cpp:1119]
0x00007fcf7e00fbec libUnrealEditor-VulkanRHI.so!FVulkanCommandListContext::RHIEndDrawingViewport(FRHIViewport*, bool, bool) [/home/sbbg/Shared/UE5/UE-5.6/Engi
ne/Source/./Runtime/VulkanRHI/Private/VulkanRHI.cpp:1273]
0x00007fd0d68700dd libUnrealEditor-RHI.so!FRHICommand<FRHICommandEndDrawingViewport, FRHICommandEndDrawingViewportString2524>::ExecuteAndDestruct(FRHICommandL
istBase&) [/home/sbbg/Shared/UE5/UE-5.6/Engine/Source/Runtime/RHI/Public/RHICommandListCommandExecutes.inl:591]
0x00007fd0d682a6ad libUnrealEditor-RHI.so!FRHICommandListBase::Execute() [/home/sbbg/Shared/UE5/UE-5.6/Engine/Source/./Runtime/RHI/Private/RHICommandList.cpp:
527]
0x00007fd0d682cfd9 libUnrealEditor-RHI.so!FRHICommandListExecutor::FTranslateState::Translate(FRHICommandListBase*) [/home/sbbg/Shared/UE5/UE-5.6/Engine/Sourc
e/./Runtime/RHI/Private/RHICommandList.cpp:1077]
0x00007fd0d6848e50 libUnrealEditor-RHI.so!UE::Core::Private::Function::TFunctionRefCaller<FRHICommandListExecutor::FSubmitState::Dispatch(FRHICommandListBase*
)::$_0, void>::Call(void*) [/home/sbbg/Shared/UE5/UE-5.6/Engine/Source/./Runtime/RHI/Private/RHICommandList.cpp:1028]
0x00007fd0d682ae85 libUnrealEditor-RHI.so!FRHICommandListExecutor::FTaskPipe::Execute(FRHICommandListExecutor::FTaskPipe::FTask*, TRefCountPtr<FBaseGraphTask>
const&) const [/home/sbbg/Shared/UE5/UE-5.6/Engine/Source/Runtime/Core/Public/Templates/Function.h:471]
0x00007fd0dee58bb5 libUnrealEditor-Core.so!TGraphTask<TFunctionGraphTaskImpl<void (ENamedThreads::Type, TRefCountPtr<FBaseGraphTask> const&), (ESubsequentsMod
e::Type)0> >::ExecuteTask() [/home/sbbg/Shared/UE5/UE-5.6/Engine/Source/Runtime/Core/Public/Templates/Function.h:471]
0x00007fd0de6e4095 libUnrealEditor-Core.so!UE::Tasks::Private::FTaskBase::TryExecuteTask() [/home/sbbg/Shared/UE5/UE-5.6/Engine/Source/Runtime/Core/Public/Tas
ks/TaskPrivate.h:527]
0x00007fd0de6e2a2d libUnrealEditor-Core.so!FNamedTaskThread::ProcessTasksNamedThread(int, bool) [/home/sbbg/Shared/UE5/UE-5.6/Engine/Source/Runtime/Core/Publi
c/Async/TaskGraphInterfaces.h:505]
0x00007fd0de6e0c6f libUnrealEditor-Core.so!FNamedTaskThread::ProcessTasksUntilQuit(int) [/home/sbbg/Shared/UE5/UE-5.6/Engine/Source/./Runtime/Core/Private/Asy
nc/TaskGraph.cpp:667]
0x00007fd0d6c599d9 libUnrealEditor-RenderCore.so!FRHIThread::Run() [/home/sbbg/Shared/UE5/UE-5.6/Engine/Source/./Runtime/RenderCore/Private/RenderingThread.cp
p:270]
0x00007fd0de8bf5a6 libUnrealEditor-Core.so!FRunnableThreadPThread::Run() [/home/sbbg/Shared/UE5/UE-5.6/Engine/Source/./Runtime/Core/Private/HAL/PThreadRunnabl
eThread.cpp:25]
0x00007fd0de811b4a libUnrealEditor-Core.so!FRunnableThreadPThread::_ThreadProc(void*) [/home/sbbg/Shared/UE5/UE-5.6/Engine/Source/Runtime/Core/Private/HAL/PTh
readRunnableThread.h:187]
0x00007fd0d1c61b1e libc.so.6!UnknownFunction(0x94b1d)
0x00007fd0d1ce4d4c libc.so.6!UnknownFunction(0x117d4b)

lorezio23 · June 4, 2025, 12:24pm

exact same issue with here, and more complex maps are extremely slow and eventually crash. The only workaround I’ve found for now is to disable SM6, but obviously this is not a solution

EDIT:
It does look like a driver issue, according to this mesa issue

RADV_DEBUG=hang works for me too and I was able to open the project with SM6 enabled

Can you try it out? I’ve just did RADV_DEBUG=hang ./Engine/Binaries/Linux/UnrealEditor and then open the project within that editor instance

sbbg · June 4, 2025, 1:46pm

Wow, it actually works. I can’t imagine how can I figure this out. Mine is Radeon 6800S. Thank you.

Phaylali · June 5, 2025, 12:22pm

you’re a true life saver, I can confirm that the new third person template on unreal engine 5.6 works on AMD Radeon 6700XT , although Fab and Bridge are not working , they show ERR_NAME_NOT_RESOLVED (-150) , Fab did work on 5.5.4 on this same machine but it didn’t work on 5.6 preview nor stable.

johnManganelli · June 5, 2025, 2:49pm

For me too both Fab and Bridge are not working , the error show ERR_NAME_NOT_RESOLVED (-150) and in the log i get: LogFab: Error: Login failed - error code: EOS_InvalidAuth
LogFab: Display: Logging in using exchange code
LogFab: Display: Reading exchange code from commandline
LogEOSSDK: Error: LogEOSAuth: Invalid parameter EOS_Auth_Credentials.Token reason: must not be null or empty
LogFab: Error: Login failed - error code: EOS_InvalidParameters

Phaylali · June 5, 2025, 11:39pm

I spent the day trying to figure out a way , and now I give up, I tried running unreal engine 5.6 from lutris and it works perfectly , surprisingly enough , the fps in lutris is better than native , fab is working , bridge is working , my metahumans are showing up , everything seems to be working , third person new template combat works out of the box, I see some flicker where there is some tooltip showing up but that’s it , try lutris , install epic games launcher, install unreal engine , fab and bridge from the epic games launcher,

lorezio23 · June 6, 2025, 7:59am

I have the same issue with Fab, it looks like it does some auth flow but then gives the ERR_NAME_NOT_RESOLVED . I’ll see if I can figure it out from the plugin code

Phaylali · June 6, 2025, 8:40am

until they can fix it , you can use unreal engine from lutris’s epic games launcher

lorezio23 · June 6, 2025, 10:05am

ok, I’ve found a workaround for fab as well.

Findings

Basically the issue seems to be with the new system dns:

/lib64/libnss_resolve.so.2: error: symbol lookup error: undefined symbol: _nss_resolve_endaliasent (fatal)

(can be seen with LD_DEBUG=libs ./Engine/Binaries/Linux/UnrealEditor)

a temporary workaround is to change the nsswitch.conf (use authselect when you verify the below works - read below for authselect instructions)

cat /etc/nsswitch.conf
# Generated by authselect
# Do not modify this file manually, use authselect instead. Any user changes will be overwritten.
# You can stop authselect from managing your configuration by calling 'authselect opt-out'.
# See authselect(8) for more details.

# In order of likelihood of use to accelerate lookup.
passwd:     files systemd
shadow:     files systemd
group:      files [SUCCESS=merge] systemd
#hosts:      files myhostname mdns4_minimal [NOTFOUND=return] resolve [!UNAVAIL=return] dns
hosts: files dns # CHANGE ABOVE TO THIS TAKE BACKUPS
services:   files
netgroup:   files
automount:  files

aliases:    files
ethers:     files
gshadow:    files systemd
networks:   files dns
protocols:  files
publickey:  files
rpc:        files

Authselect

sudo authselect create-profile custom-nss --base-on=local
sudo vi /etc/authselect/custom/custom-nss/nsswitch.conf

and do the changes
moving dns after files myhostname also works

Then when using unreal (this can also be done when unreal is running, on a different session) you can do
sudo authselect select custom/custom-nss --force

Comments

It does look like the getaddrinfo crashes when the dns reaches resolve stage

I guess the issue is the packaged libraries might not be compatible with some system libraries, but I haven’t spent too much time on this.

It does solve the issue for me, maybe another day I’ll dig deeper (maybe a libcef update is needed, I don’t know, I have an older ubuntu machine , it may work there, when I’m on it I’ll update here)

B4rr3l · June 6, 2025, 1:21pm

I’m having this issue even with RADV_DEBUG=hang:

LoginId:010149f18d744f8b8f45bcbaf7986948-000003e8

Caught signal 11 Segmentation fault

libdxcompiler.so!_ZN8spvtools25SetContextMessageConsumerEP13spv_context_tNSt3__18functionIFv19spv_message_level_tPKcRK14spv_position_tS6_EEE(+0x31)
libdxcompiler.so!_ZN8spvtools10SpirvTools18SetMessageConsumerENSt3__18functionIFv19spv_message_level_tPKcRK14spv_position_tS5_EEE(+0x54)
libdxcompiler.so!_ZNK8spvtools9Optimizer3RunEPKjmPNSt3__16vectorIjNS3_9allocatorIjEEEEP23spv_optimizer_options_t(+0x7f)
libdxcompiler.so!UnknownFunction(0xdd98b1)
libdxcompiler.so!UnknownFunction(0xdd8232)
libdxcompiler.so!UnknownFunction(0xe973d1)
libdxcompiler.so!UnknownFunction(0x7beeb8)
libdxcompiler.so!UnknownFunction(0x21a0f0)
libdxcompiler.so!UnknownFunction(0x215287)
libdxcompiler.so!UnknownFunction(0x2161d5)
libdxcompiler.so!UnknownFunction(0x216b77)
libShaderConductor.so!UnknownFunction(0xb1620)
libShaderConductor.so!_ZN15ShaderConductor8Compiler7CompileERKNS0_10SourceDescERKNS0_7OptionsEPKNS0_10TargetDescEjPNS0_10ResultDescE(+0x3dc)
libShaderConductor.so!_ZN15ShaderConductor8Compiler7CompileERKNS0_10SourceDescERKNS0_7OptionsERKNS0_10TargetDescE(+0x51)
libUnrealEditor-ShaderCompilerCommon.so!CrossCompiler::FShaderConductorContext::CompileHlslToSpirv(CrossCompiler::FShaderConductorOptions const&, TArray<unsigned int, TSizedDefaultAllocator<32> >&) [/mnt/horde/++UE5/Sync/Engine/Source/./Developer/ShaderCompilerCommon/Private/ShaderConductorContext.cpp:34]
libUnrealEditor-VulkanShaderFormat.so!SpirvShaderCompiler::CompileWithShaderConductor(FSpirvShaderCompilerInternalState const&, TStringView, SpirvShaderCompilerSerializedOutput&, FShaderCompilerOutput&) [/mnt/horde/++UE5/Sync/Engine/Source/./Developer/VulkanShaderFormat/Private/SpirVShaderCompiler.inl:1364]
libUnrealEditor-VulkanShaderFormat.so!CompileVulkanShader(FShaderCompilerInput const&, FShaderPreprocessOutput const&, FShaderCompilerOutput&, FString const&) [/mnt/horde/++UE5/Sync/Engine/Source/./Developer/VulkanShaderFormat/Private/VulkanShaderCompiler.cpp:327]
libUnrealEditor-RenderCore.so!FInternalShaderCompilerFunctions::CompileShaderInternal(IShaderFormat const*, FShaderCompileJob&, FString const&, FString&, FString&, int*) [/mnt/horde/++UE5/Sync/Engine/Source/./Runtime/RenderCore/Private/ShaderCore.cpp:1762]
libUnrealEditor-RenderCore.so!CompileShader(TArray<IShaderFormat const*, TSizedDefaultAllocator<32> > const&, FShaderCompileJob&, FString const&, int*) [/mnt/horde/++UE5/Sync/Engine/Source/./Runtime/RenderCore/Private/ShaderCore.cpp:1909]
libUnrealEditor-Engine.so!FShaderCompileUtilities::ExecuteShaderCompileJob(FShaderCommonCompileJob&) [/mnt/horde/++UE5/Sync/Engine/Source/./Runtime/Engine/Private/ShaderCompiler/ShaderCompilerUtil.cpp:870]
libUnrealEditor-Engine.so!FShaderCompileThreadRunnable::CompileDirectlyThroughDll() [/mnt/horde/++UE5/Sync/Engine/Source/./Runtime/Engine/Private/ShaderCompiler/ShaderCompilerThreadRunnable.cpp:843]
libUnrealEditor-Engine.so!FShaderCompileThreadRunnable::CompilingLoop() [/mnt/horde/++UE5/Sync/Engine/Source/./Runtime/Engine/Private/ShaderCompiler/ShaderCompilerThreadRunnable.cpp:1331]
libUnrealEditor-Engine.so!FShaderCompileThreadRunnableBase::Run() [/mnt/horde/++UE5/Sync/Engine/Source/./Runtime/Engine/Private/ShaderCompiler/ShaderCompilerThreadRunnable.cpp:304]
libUnrealEditor-Core.so!FRunnableThreadPThread::Run() [/mnt/horde/++UE5/Sync/Engine/Source/./Runtime/Core/Private/HAL/PThreadRunnableThread.cpp:25]
libUnrealEditor-Core.so!FRunnableThreadPThread::_ThreadProc(void*) [/mnt/horde/++UE5/Sync/Engine/Source/Runtime/Core/Private/HAL/PThreadRunnableThread.h:187]
libc.so.6!UnknownFunction(0x99545)
libc.so.6!UnknownFunction(0x11d94b)

johnManganelli · June 8, 2025, 10:12am

Thanks man, but for me that solves only part of the problem, after i done the authselect part my engine started to show other error when trying to use fab “/usr/lib64/pkcs11/p11-kit-trust.so: error: symbol lookup error: undefined symbol: C_GetInterface (fatal)”

But for luck for me to make all work in Fedora i just needed to install the p11-kit-client x86_64 package and try to open and close 2 times the Fab window, probably that is a problem in the Rawhide

thanks for the help

Barney_Stinson_X · June 11, 2025, 4:40pm

Thanks, it’s worked for me as well

iHad169 · June 14, 2025, 3:13pm

I is Radeon 6700XT worked in RADV_DEBUG=hang
Thank you

kshots · July 17, 2025, 1:51pm

← This

Fixed my problem with FAB, wasn’t even looking for a solution at the time, was trying to resolve the OP’s issue - this thread gives a valid workaround for both problems. Many thanks, hopefully Epic will fix the nsswitch incompatibility and AMD will fix the GPU hang issue.

EDIT: Spoke too soon on the first (OP) issue - yes, it works partially… instead of hanging the GPU at start on a simple template project, it will work (well) for about 20 minutes… then hang the GPU. In this case, it hanged hard, and it persisted across reboots - I had to let the machine cool down for an hour or so before I could use it reliably again. I think I’m done playing around with this and will wait for a driver update

For reference, I’m on an RX 7900M (laptop)