Beta tester experiencing Fatal error! on packaged debug game

We’re distributing debug builds of our game to some testers, and one of them has a ‘Fatal error!’ on start up - this is their log:

Log file open, 07/01/16 19:31:37

LogConsoleManager:Warning: Console object named ‘D3D12.EnableMultiEngine’ already exists but is being registered again, but we weren’t expected it to be! (FConsoleManager::AddConsoleObject)

LogConsoleManager:Warning: Console object named ‘D3D12.EnableMultiEngine’ already exists but is being registered again, but we weren’t expected it to be! (FConsoleManager::AddConsoleObject)

LogModuleManager:Warning: ModuleManager: Module ‘HTTPChunkInstaller’ not found - its StaticallyLinkedModuleInitializers function is null.

LogPlatformFile: Not using cached read wrapper

LogInit:Display: RandInit(-1272277992) SRandInit(-1272277991).

LogTaskGraph: Started task graph with 4 named threads and 7 total threads.

LogStats: Stats thread started at 0.057728

LogTemp:Warning: Failed to load LeapMotion library.

LeapPluginLog: Using LeapPlugin version 2.0.0

LogWindows:Warning: CreateProc failed (2) …....\Engine\Binaries/Win64/CrashReportClient.exe -AppName=UE4->VirtualNovel -DebugSymbols=…....\Engine\Intermediate\Symbols

LogWindows: Could not start CrashReportClient.exe

LogMemory: Platform Memory Stats for WindowsNoEditor

LogMemory: Process Physical Memory: 35.83 MB used, 35.84 MB peak

LogMemory: Process Virtual Memory: 20.78 MB used, 20.82 MB peak

LogMemory: Physical Memory: 4460.91 MB used, 16344.06 MB total

LogMemory: Virtual Memory: 238.49 MB used, 134217728.00 MB total

LogWindows:Error: === Critical error: ===

Fatal error!

LogWindows: FPlatformMisc::RequestExit(1)

Log file closed, 07/01/16 19:31:38

There is only one out of many testers experiencing this problem, is there anything in this log that would help me to diagnose the issue for their particular case? The OS is Window 10.

Repackaged with UE4 prerequisites and it solved it.