Fatal Error Opening Project

Just tried to open my project and this keeps popping up.
Any Ideas?!
I have been working on this project for a couple of months now and could do with it back!

Thanks for the answers!

MachineId:4371A33345BAF60C1ED89292135D974B
EpicAccountId:4225e9eeb509424bb50bbf58711316dc

Unknown exception - code 00000001 (first/second chance not available)

"Fatal error: [File:D:\BuildFarm\buildmachine_++depot+UE4-Releases+4.10\Engine\Source\Runtime\Engine\Private\Materials\MaterialShared.cpp] [Line: 1395]
Failed to compile default material WorldGrid

UE4Editor_Core!FDebug::AssertFailed() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.10\engine\source\runtime\core\private\misc\outputdevice.cpp:374]
UE4Editor_Engine!FMaterial::CacheShaders() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.10\engine\source\runtime\engine\private\materials\materialshared.cpp:1395]
UE4Editor_Engine!FMaterial::CacheShaders() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.10\engine\source\runtime\engine\private\materials\materialshared.cpp:1291]
UE4Editor_Engine!UMaterial::CacheShadersForResources() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.10\engine\source\runtime\engine\private\materials\material.cpp:1902]
UE4Editor_Engine!UMaterial::CacheResourceShadersForRendering() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.10\engine\source\runtime\engine\private\materials\material.cpp:1820]
UE4Editor_Engine!UMaterial::PostLoad() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.10\engine\source\runtime\engine\private\materials\material.cpp:2448]
UE4Editor_CoreUObject!UObject::ConditionalPostLoad() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.10\engine\source\runtime\coreuobject\private\uobject\obj.cpp:723]
UE4Editor_Engine!UMaterialInterface::PostLoadDefaultMaterials() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.10\engine\source\runtime\engine\private\materials\material.cpp:387]
UE4Editor_Engine!UMaterial::PostLoad() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.10\engine\source\runtime\engine\private\materials\material.cpp:2297]
UE4Editor_CoreUObject!UObject::ConditionalPostLoad() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.10\engine\source\runtime\coreuobject\private\uobject\obj.cpp:723]
UE4Editor_CoreUObject!EndLoad() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.10\engine\source\runtime\coreuobject\private\uobject\uobjectglobals.cpp:1286]
UE4Editor_CoreUObject!LoadPackageInternal() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.10\engine\source\runtime\coreuobject\private\uobject\uobjectglobals.cpp:1042]
UE4Editor_CoreUObject!ResolveName() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.10\engine\source\runtime\coreuobject\private\uobject\uobjectglobals.cpp:681]
UE4Editor_CoreUObject!StaticLoadObjectInternal() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.10\engine\source\runtime\coreuobject\private\uobject\uobjectglobals.cpp:768]
UE4Editor_CoreUObject!StaticLoadObject() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.10\engine\source\runtime\coreuobject\private\uobject\uobjectglobals.cpp:832]
UE4Editor_UMG!ConstructorHelpersInternal::FindOrLoadObject() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.10\engine\source\runtime\coreuobject\public\uobject\constructorhelpers.h:32]
UE4Editor_UMG!ConstructorHelpers::FObjectFinder::FObjectFinder() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.10\engine\source\runtime\coreuobject\public\uobject\constructorhelpers.h:104]
UE4Editor_UMG!UWidgetComponent::UWidgetComponent() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.10\engine\source\runtime\umg\private\components\widgetcomponent.cpp:504]
UE4Editor_CoreUObject!UClass::CreateDefaultObject() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.10\engine\source\runtime\coreuobject\private\uobject\class.cpp:2657]
UE4Editor_CoreUObject!UObjectLoadAllCompiledInDefaultProperties() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.10\engine\source\runtime\coreuobject\private\uobject\uobjectbase.cpp:658]
UE4Editor_CoreUObject!ProcessNewlyLoadedUObjects() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.10\engine\source\runtime\coreuobject\private\uobject\uobjectbase.cpp:752]
UE4Editor!FEngineLoop::PreInit() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.10\engine\source\runtime\launch\private\launchengineloop.cpp:1392]
UE4Editor!GuardedMain() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.10\engine\source\runtime\launch\private\launch.cpp:110]
UE4Editor!GuardedMainWrapper() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.10\engine\source\runtime\launch\private\windows\launchwindows.cpp:126]
UE4Editor!WinMain() [d:\buildfarm\buildmachine_++depot+ue4-releases+4.10\engine\source\runtime\launch\private\windows\launchwindows.cpp:200]
UE4Editor!__scrt_common_main_seh() [f:\dd\vctools\crt\vcstartup\src\startup\exe_common.inl:264]
kernel32
ntdll

I assume your are using the same machine that you opened it the last time?

Maybe this helps?
https://answers.unrealengine.com/questions/125129/debugging-failed-to-compile-material.html