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Fatal Error crashes on servertravel

In 4.16.1 there are a constant amount of unknown fatal error crashes that occur on servertravel.

 [2017.06.20-17.57.33:751][ 91]LogWindows:Warning: CreateProc failed (2) ../../../Engine/Binaries/Win64/CrashReportClient.exe "H:/GAME/WindowsNoEditor/WindowsNoEditor/Game/Saved/Crashes/UE4CC-Windows-4C804C9F41BF70FD2E8273BEE08A4110_0000" -AppName=UE4-Game -CrashGUID=UE4CC-Windows-4C804C9F41BF70FD2E8273BEE08A4110_0000 -DebugSymbols=..\..\..\Engine\Intermediate\Symbols
 [2017.06.20-17.57.33:751][ 91]LogWindows: Could not start CrashReportClient.exe
 [2017.06.20-17.57.33:751][ 91]LogMemory: Platform Memory Stats for WindowsNoEditor
 [2017.06.20-17.57.33:751][ 91]LogMemory: Process Physical Memory: 1117.67 MB used, 1118.00 MB peak
 [2017.06.20-17.57.33:751][ 91]LogMemory: Process Virtual Memory: 2442.87 MB used, 3331.46 MB peak
 [2017.06.20-17.57.33:751][ 91]LogMemory: Physical Memory: 8041.95 MB used,  16525.16 MB free, 24567.11 MB total
 [2017.06.20-17.57.33:751][ 91]LogMemory: Virtual Memory: 3092.70 MB used,  16525.16 MB free, 8388608.00 MB total
 [2017.06.20-17.57.33:751][ 91]LogThreadingWindows:Error: Runnable thread PoolThread 4 crashed.
 [2017.06.20-17.57.33:751][ 91]LogWindows:Error: === Critical error: ===
 [2017.06.20-17.57.33:751][ 91]LogWindows:Error: 
 [2017.06.20-17.57.33:751][ 91]LogWindows:Error: Fatal error!
 [2017.06.20-17.57.33:751][ 91]LogWindows:Error: 
 [2017.06.20-17.57.33:751][ 91]LogWindows:Error: Unhandled Exception: EXCEPTION_ACCESS_VIOLATION reading address 0x00000030
 [2017.06.20-17.57.33:751][ 91]LogWindows:Error: 

These crashes never occured in 4.15.2, and they are very inconsistent. Sometimes after starting the game on 2 separate machines, you can servertravel between 4-5 levels, and other times it will fatal crash on the very fist servertravel...

Product Version: UE 4.16
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asked Jun 20 '17 at 06:13 PM in Bug Reports

avatar image

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avatar image MADHOUSE Jun 20 '17 at 09:46 PM

Exception thrown at 0x00000001410BADAB in Game-Win64-Shipping.exe: 0xC0000005: Access violation reading location 0x0000000100000030.

After debugging the crash in visual studio the crash seems to happen at this breakpoint:

 void RequestIsComplete()
         if (!bCanceled && Priority > AIOP_Precache)
         FScopeLock Lock(&FPakReadRequestEvent);
         bRequestOutstanding = false;
         if (WaitEvent)
             WaitEvent->Trigger();     (<----BREAK POINT)

This function is in IPlatformFilePak.cpp

avatar image MADHOUSE Jun 20 '17 at 11:28 PM

Since the crash seems related to *.pak file loading/reading at servertravel, I tested to build and package the project with pak files disabled. This stops all crashes at servertravel, altho the resulting project build is twice the size and it is obviously not an acceptable solution that can be shipped..

avatar image Sean L ♦♦ STAFF Jun 21 '17 at 07:32 PM


I gave this a shot in my test project, but I didn't see any crashes occur in 4.16.1. Could you please provide the logs so I can take a look at those, as well as give this a shot in a clean project and let me know if you're seeing it there too.


avatar image MADHOUSE Jun 21 '17 at 09:58 PM

I will investigate as much as I can, I suspect there might be a need to put larger amount of data into the pak to cause these issues. It could be usefull to have an engineer look at this section of code since this issue did not happen before 4.16. Someone with more insight into what has changed and why this would happen could perhaps shed more light on it.

On my end all I can do is process-of-elimination which might take a while to analyse.

avatar image MADHOUSE Jun 28 '17 at 11:37 PM

alt text

Crash log: https://pastebin.com/DpZqMi7m

This issue is currently critical and shipping breaking.

avatar image MADHOUSE Jun 29 '17 at 10:23 PM

and sometimes the crash provides less information then in the log above, but still relates to IPlatformFilePak.cpp : https://pastebin.com/dcd7NKFj

avatar image MADHOUSE Jul 02 '17 at 05:27 PM

These crashes still occur in 4.16.2..

avatar image MADHOUSE Jul 04 '17 at 09:47 PM

Any news on this?

avatar image nrossol Jun 25 '17 at 05:16 PM

By any chance, are any of your Levels performing a Multicast call from inside a Level Blueprint? If so, it's possible that's it's related to a confirmed 4.16 Engine bug I recently posted here:


avatar image MADHOUSE Jun 25 '17 at 07:01 PM

Greetings. Hmm interesting, some of the levels are indeed using multicast RPC's to reset states on level actors during match restarts, I'll look into it this week and return with results, it could very well be the related to the same issue.

Thanks for the information!

avatar image MADHOUSE Jun 28 '17 at 10:53 PM

Im still getting fatal error crashes. Debugging in visual studio still breaks at this function in IPlatformFilePak.cpp altho I haven't seen more "Level was reloaded before it even closed the linker from a previous load." crashes yet, so I cant tell if they are related. I have had quite a few of those in the past aswell.

avatar image Sean L ♦♦ STAFF Jul 20 '17 at 05:34 PM

Thanks for the heads up, I've assigned your ticket out for investigation.

avatar image MADHOUSE Jul 20 '17 at 08:43 PM

There is definitely something wierd going on there when the engine attempts to read or serialize content from the pak file. At the assertion break the WaitEvent / Trigger event reference/value is null, as well as almost all variables in that section.

          if (WaitEvent)

Resulting in crash: EXCEPTION_ACCESS_VIOLATION reading address 0xffffffff

Please post back if there is any progress on this issue. This problem is still shipping breaking.

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I've reproduced a crash on Server Travel that was reported by nrossol, and entered that ticket here: https://issues.unrealengine.com/issue/UE-46854

If you're seeing something different, I haven't been able to reproduce that on my end, so unfortunately I can't get a ticket in for that just yet. If you're able to narrow it down and provide me with a repro case or a project I can use, I'd be glad to take another look at it.


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answered Jul 05 '17 at 07:49 PM

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Sean L ♦♦ STAFF
43.6k 485 152 441

avatar image MADHOUSE Jul 05 '17 at 08:54 PM

Greetings. I have also had problems with UE-46854, altho this is a different issue unfortunately. I'll explore the issue some more this week and see If I can find any more information..

I'll post back if I have any results. The issue is there obviously but it seems very very low-level and its difficult to debug on my end so it might take some time.

Best Regards

avatar image MADHOUSE Jul 25 '17 at 03:20 AM

Sometimes this is the error crash details, and a bit different from the more usual crash log and messages:

avatar image MADHOUSE Jul 25 '17 at 03:29 AM
 Error: Runnable thread TaskGraphThreadNP 1 crashed.
 === Critical error: ===
 Fatal error: [File:H:\UnrealEngine-release\Engine\Source\Runtime\Core\Private\Windows\WindowsPlatformMisc.cpp] [Line: 482] 
 Pure virtual function being called
 Game.exe!FOutputDeviceWindowsError::Serialize() [h:\unrealengine-release\engine\source\runtime\core\private\windows\windowsplatformoutputdevices.cpp:120]
 Game.exe!FOutputDevice::Logf__VA() [h:\unrealengine-release\engine\source\runtime\core\private\misc\outputdevice.cpp:70]
 Game.exe!FDebug::AssertFailed() [h:\unrealengine-release\engine\source\runtime\core\private\misc\assertionmacros.cpp:349]
 Game.exe!FPakProcessedReadRequest::RequestIsComplete() [h:\unrealengine-release\engine\source\runtime\pakfile\private\iplatformfilepak.cpp:2740]
 Game.exe!FPakAsyncReadFileHandle:oProcessing() [h:\unrealengine-release\engine\source\runtime\pakfile\private\iplatformfilepak.cpp:3079]
 Game.exe!TGraphTask<FAsyncIOCPUWorkTask>::ExecuteTask() [h:\unrealengine-release\engine\source\runtime\core\public\async\taskgraphinterfaces.h:886]
 Game.exe!FTaskThreadAnyThread::ProcessTasks() [h:\unrealengine-release\engine\source\runtime\core\private\async\taskgraph.cpp:1277]
 Game.exe!FTaskThreadAnyThread::ProcessTasksUntilQuit() [h:\unrealengine-release\engine\source\runtime\core\private\async\taskgraph.cpp:1171]
 Game.exe!FTaskThreadBase::Run() [h:\unrealengine-release\engine\source\runtime\core\private\async\taskgraph.cpp:643]
 Game.exe!FRunnableThreadWin::Run() [h:\unrealengine-release\engine\source\runtime\core\private\windows\windowsrunnablethread.cpp:76]
 Game.exe!FRunnableThreadWin::GuardedRun() [h:\unrealengine-release\engine\source\runtime\core\private\windows\windowsrunnablethread.cpp:33]
avatar image MADHOUSE Jul 27 '17 at 03:19 AM

This bug seems to be gone in 4.17 preview 3.

avatar image MADHOUSE Aug 23 '17 at 09:58 PM

We just finished a playtest with a 4.17.1 build of my project and there still are crashes on servertravel, but it gives no crash messages and only gets stuck in a black screen / freeze.

This unfortunately happens so much that in an online session with 5-6 players, atleast one will crash out every servertravel.

avatar image MADHOUSE Aug 23 '17 at 11:07 PM

I've run the game with VS debugger now to look at what happens when it freezes during servertravel, it does not trigger a break or anything, but pausing at the freeze stops here in ThreadingBase.cpp:

[External Code]

Game-Win64-Shipping.exe!FEventWin::Wait(unsigned int WaitTime, const bool bIgnoreThreadIdleStats) Line 1159 C++ Game-Win64-Shipping.exe!FQueuedThread::Run() Line 451 C++ Game-Win64-Shipping.exe!FRunnableThreadWin::Run() Line 76 C++ Game-Win64-Shipping.exe!FRunnableThreadWin::GuardedRun() Line 33 C++

[External Code]

and it seems to just wait indefinitely and the engine is completely idle.

avatar image MADHOUSE Aug 24 '17 at 10:43 PM

These crashes/freezes seems to stop when disabled nativizing assets. Probably related to other issues with nativized assets in 4.17:


avatar image Sean L ♦♦ STAFF Sep 07 '17 at 12:53 PM


Apologies for the delay on this. Unfortunately, I haven't been able to reproduce a similar issue, nor have I seen anything like this pop up in our database at this time. With regards to your latest comment, I'll go ahead and close this topic for now since disabling nativization resolves the crash, as it is likely related to the issue you posted in your linked ticket. If you still experience an issue with it once that issue gets resolved, feel free to leave a comment to reopen the thread.

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