This is common crash coming out of the 4.17 and 4.18 releases. The callstack is similar to an old unresolved import crash: [Link Removed]
User Descriptions
Source Context
494 virtual bool Seek(int64 NewPosition) override
495 {
496 check(IsValid());
497 check(NewPosition >= 0);
498 check(NewPosition <= FileSize);
499
500 ***** FilePos = NewPosition;
501 UpdateOverlappedPos();
502 return true;
503 }
repro steps currently unknown; but related to building lighting
Assertion failed: NewPosition <= FileSize [File:D:\Build\++UE4+Release-4.17+Compile\Sync\Engine\Source\Runtime\Core\Private\Windows\WindowsPlatformFile.cpp] [Line: 499] UE4Editor_Core!FFileHandleWindows::Seek() [windowsplatformfile.cpp:501] UE4Editor_Core!FArchiveFileWriterGeneric::Seek() [filemanagergeneric.cpp:796] UE4Editor_CoreUObject!UPackage::Save() [savepackage.cpp:5100] UE4Editor_UnrealEd!UEditorEngine::Save() [editorengine.cpp:4210] UE4Editor_UnrealEd!UEditorEngine::SavePackage() [editorengine.cpp:4268] UE4Editor_UnrealEd!UEditorEngine::Exec_Obj() [editorserver.cpp:4431] UE4Editor_UnrealEd!UEditorEngine::Exec() [editorserver.cpp:5526] UE4Editor_UnrealEd!UUnrealEdEngine::Exec() [unrealedsrv.cpp:672] UE4Editor_UnrealEd!FEditorFileUtils::AutosaveContentPackagesEx() [filehelpers.cpp:2453] UE4Editor_UnrealEd!FPackageAutoSaver::AttemptAutoSave() [packageautosaver.cpp:206] UE4Editor_UnrealEd!UUnrealEdEngine::Tick() [unrealedengine.cpp:430] UE4Editor!FEngineLoop::Tick() [launchengineloop.cpp:3215] UE4Editor!GuardedMain() [launch.cpp:166] UE4Editor!GuardedMainWrapper() [launchwindows.cpp:134] UE4Editor!WinMain() [launchwindows.cpp:210] UE4Editor!__scrt_common_main_seh() [exe_common.inl:253] kernel32!BaseThreadInitThunk() ntdll!RtlUserThreadStart()
There's no existing public thread on this issue, so head over to Questions & Answers just mention UE-48975 in the post.