Unreal Engine 4 Random Crashes

Hi!
Since 1 or 2 days Unreal Engine 4 recenlty crashes randomly. Its something with TextureRenderTarget2D_5 and with Widget3DPassThrough

This is the log file:

    [2018.09.02-12.53.40:825][946]LogWindows: Error: === Critical error: ===
    [2018.09.02-12.53.40:825][946]LogWindows: Error: 
    [2018.09.02-12.53.40:825][946]LogWindows: Error: Fatal error: [File:D:\Build\++UE4+Release-4.19+Compile\Sync\Engine\Source\Runtime\RenderCore\Private\RenderingThread.cpp] [Line: 819] 
    [2018.09.02-12.53.40:825][946]LogWindows: Error: Rendering thread exception:
    [2018.09.02-12.53.40:825][946]LogWindows: Error: Assertion failed: Value->TextureReference.TextureReferenceRHI [File:D:\Build\++UE4+Release-4.19+Compile\Sync\Engine\Source\Runtime\Engine\Private\Materials\MaterialUniformExpressions.cpp] [Line: 436] 
    [2018.09.02-12.53.40:825][946]LogWindows: Error: Texture TextureRenderTarget2D_5 of class TextureRenderTarget2D had invalid texture reference. Material Widget3DPassThrough with texture expression in slot 0
    [2018.09.02-12.53.40:825][946]LogWindows: Error: 
    [2018.09.02-12.53.40:825][946]LogWindows: Error: 
    [2018.09.02-12.53.40:825][946]LogWindows: Error: [Callstack] 0x00000000FD67A06D KERNELBASE.dll!UnknownFunction []
    [2018.09.02-12.53.40:825][946]LogWindows: Error: [Callstack] 0x00000000F9AD7884 UE4Editor-ApplicationCore.dll!UnknownFunction []
    [2018.09.02-12.53.40:825][946]LogWindows: Error: [Callstack] 0x00000000D63D6D9B UE4Editor-Core.dll!UnknownFunction []
    [2018.09.02-12.53.40:825][946]LogWindows: Error: [Callstack] 0x00000000D6311949 UE4Editor-Core.dll!UnknownFunction []
    [2018.09.02-12.53.40:825][946]LogWindows: Error: [Callstack] 0x00000000D4190730 UE4Editor-Engine.dll!UnknownFunction []
    [2018.09.02-12.53.40:825][946]LogWindows: Error: [Callstack] 0x00000000D4198B38 UE4Editor-Engine.dll!UnknownFunction []
    [2018.09.02-12.53.40:825][946]LogWindows: Error: [Callstack] 0x00000000D415C85B UE4Editor-Engine.dll!UnknownFunction []
    [2018.09.02-12.53.40:825][946]LogWindows: Error: [Callstack] 0x00000000D41E65A1 UE4Editor-Engine.dll!UnknownFunction []
    [2018.09.02-12.53.40:825][946]LogWindows: Error: [Callstack] 0x00000000CA15EC3B UE4Editor-SlateRHIRenderer.dll!UnknownFunction []
    [2018.09.02-12.53.40:825][946]LogWindows: Error: [Callstack] 0x00000000CA167C4C UE4Editor-SlateRHIRenderer.dll!UnknownFunction []
    [2018.09.02-12.53.40:825][946]LogWindows: Error: [Callstack] 0x00000000D61EB713 UE4Editor-Core.dll!UnknownFunction []
    [2018.09.02-12.53.40:825][946]LogWindows: Error: [Callstack] 0x00000000D61EBD3A UE4Editor-Core.dll!UnknownFunction []
    [2018.09.02-12.53.40:825][946]LogWindows: Error: [Callstack] 0x00000000F9A63CC9 UE4Editor-RenderCore.dll!UnknownFunction []
    [2018.09.02-12.53.40:825][946]LogWindows: Error: [Callstack] 0x00000000F9A64CF6 UE4Editor-RenderCore.dll!UnknownFunction []
    [2018.09.02-12.53.40:825][946]LogWindows: Error: [Callstack] 0x00000000D65B9FFC UE4Editor-Core.dll!UnknownFunction []
    [2018.09.02-12.53.40:825][946]LogWindows: Error: [Callstack] 0x00000000D65AED63 UE4Editor-Core.dll!UnknownFunction []
    [2018.09.02-12.53.40:825][946]LogWindows: Error: [Callstack] 0x00000000777959CD kernel32.dll!UnknownFunction []
    [2018.09.02-12.53.40:825][946]LogWindows: Error: [Callstack] 0x00000000779F383D ntdll.dll!UnknownFunction []
    [2018.09.02-12.53.40:825][946]LogWindows: Error: [Callstack] 0x00000000779F383D ntdll.dll!UnknownFunction []
    [2018.09.02-12.53.40:825][946]LogWindows: Error: 
    [2018.09.02-12.53.40:825][946]LogWindows: Error: 
    [2018.09.02-12.53.40:825][946]LogWindows: Error: 
    [2018.09.02-12.53.40:825][946]LogWindows: Error: 
    [2018.09.02-12.53.40:840][946]LogExit: Executing StaticShutdownAfterError
    [2018.09.02-12.53.40:849][946]LogWindows: FPlatformMisc::RequestExit(1)
    [2018.09.02-12.53.40:849][946]Log file closed, 09/02/18 14:53:40

Do you guys have an Idea how to fix this?
Thanks in Advanceā€¦