4.8 packaged game crashes on launch with fatal error. worked on 4.7.6

Hiya.

My game used to package and be playable without an issue in 4.7.6. However in 4.8.0 I can package it fine it seems but as soon as I try and run it I get this, everytime. Anyone have any ideas on whats going on here? Any help would be appreciated. Thanks!

The log doesnt have much in it since it crashes immediately.

This is the end of it:

[2015.06.19-22.51.34:914][  0]LogStreaming:Warning: Failed to read file '../../../Engine/Content/Editor/Slate/Icons/ToParent.png' error.
[2015.06.19-22.51.34:914][  0]LogSlate: Could not find file for Slate resource: ../../../Engine/Content/Editor/Slate/Icons/ToParent.png
[2015.06.19-22.51.34:914][  0]LogStreaming:Warning: Failed to read file '../../../Engine/Content/Editor/Slate/Common/ComboArrow.png' error.
[2015.06.19-22.51.34:914][  0]LogSlate: Could not find file for Slate resource: ../../../Engine/Content/Editor/Slate/Common/ComboArrow.png
[2015.06.19-22.51.34:927][  0]LogEngine: Initializing Engine...
[2015.06.19-22.51.34:929][  0]LogHMD: Can't find Oculus library dev build: is proper Runtime installed? Version: 0.6.0.0
[2015.06.19-22.51.34:938][  0]LogHMD:Warning: SteamVR failed to initialize.  Error: 110
[2015.06.19-22.51.35:023][  0]LogInit: XAudio2 using 'Speakers (Realtek High Definition Audio)' : 2 channels at 48 kHz using 32 bits per sample (channel mask 0x3)
[2015.06.19-22.51.35:036][  0]LogInit: FAudioDevice initialized.
[2015.06.19-22.51.35:036][  0]LogInit: Texture streaming: Disabled
[2015.06.19-22.51.35:037][  0]LogAnalytics: Creating configured Analytics provider AnalyticsET
[2015.06.19-22.51.35:037][  0]LogAnalytics: [UEGame.UnrealEngine.Release|4E84E1A84CF2AD7CA0224CA0E797E10A|ConvLite] APIServer = http://et2.epicgames.com/ET2/. AppVersion = 4.8.0-2579680+++depot+UE4-Releases+4.8
[2015.06.19-22.51.35:037][  0]LogAnalytics: [UEGame.UnrealEngine.Release|4E84E1A84CF2AD7CA0224CA0E797E10A|ConvLite] SetUserId d7acd95c489b99a4b46097973af811a4|573c88c2fc7b4cc6bb23c3911bc612b3|7b887a97-b2e9-4f2f-9e71-60bb3bd06ed4
[2015.06.19-22.51.35:037][  0]LogAnalytics: [UEGame.UnrealEngine.Release|4E84E1A84CF2AD7CA0224CA0E797E10A|ConvLite] AnalyticsET::StartSession

Fatal error!

ConvMPDemo.exe {0x00007ff795c7da70} + 0 bytes
ConvMPDemo.exe {0x00007ff795ce47dc} + 0 bytes
ConvMPDemo.exe {0x00007ff79605ebce} + 0 bytes
ConvMPDemo.exe {0x00007ff79606c522} + 0 bytes
ConvMPDemo.exe {0x00007ff796074bd8} + 0 bytes
ConvMPDemo.exe {0x00007ff7960741ed} + 0 bytes
ConvMPDemo.exe {0x00007ff7967ea758} + 0 bytes
ConvMPDemo.exe {0x00007ff795c02495} + 0 bytes
ConvMPDemo.exe {0x00007ff795c01918} + 0 bytes
ConvMPDemo.exe {0x00007ff795c01c4a} + 0 bytes
ConvMPDemo.exe {0x00007ff795c14199} + 0 bytes
ConvMPDemo.exe {0x00007ff798bf48e1} + 0 bytes
KERNEL32.DLL {0x00007ffafa2613d2} + 0 bytes
ntdll.dll {0x00007ffafc225444} + 0 bytes
ntdll.dll {0x00007ffafc225444} + 0 bytes

Crash in runnable thread SlateLoadingThread

seems to be fixed in 481… had to build from source to get access