LNK2019

I’m Getting this error when trying to build my solution, I’ve been checking online and searching but I haven’t found a solution to the problem.

1> [1/5] TeddBallSpawner.gen.cpp
1> [2/5] TeddBallSpawner.cpp
1> [3/5] UE4Editor-CodeJunk-0017.lib
1> Creating library D:\Applications\Epic\Projects\CodeJunk\Intermediate\Build\Win64\UE4Editor\Development\CodeJunk\UE4Editor-CodeJunk-0017.lib
and object D:\Applications\Epic\Projects\CodeJunk\Intermediate\Build\Win64\UE4Editor\Development\CodeJunk\UE4Editor-CodeJunk-0017.exp

1> [4/5] UE4Editor-CodeJunk-0017.dll
1> Creating library D:\Applications\Epic\Projects\CodeJunk\Intermediate\Build\Win64\UE4Editor\Development\CodeJunk\UE4Editor-CodeJunk-0017.suppressed.lib
and object D:\Applications\Epic\Projects\CodeJunk\Intermediate\Build\Win64\UE4Editor\Development\CodeJunk\UE4Editor-CodeJunk-0017.suppressed.exp

1>TeddBallSpawner.cpp.obj : error LNK2019: unresolved external symbol “private: void __cdecl ATeddBallSpawner::StartSpawnTimer(void)” (?StartSpawnTimer@ATeddBallSpawner@@AEAAXXZ)
referenced in function “protected: virtual void __cdecl ATeddBallSpawner::BeginPlay(void)” (?BeginPlay@ATeddBallSpawner@@MEAAXXZ)

1>D:\Applications\Epic\Projects\CodeJunk\Binaries\Win64\UE4Editor-CodeJunk-0017.dll : fatal error LNK1120: 1 unresolved externals
1>D:\Applications\Visual Studio\IDE\MSBuild\Microsoft\VC\v160\Microsoft.MakeFile.Targets(45,5): error MSB3073:
The command “D:\Applications\Epic\UE4\UE_4.27\Engine\Build\BatchFiles\Build.bat CodeJunkEditor Win64 Development -Project=“D:\Applications\Epic\Projects\CodeJunk\CodeJunk.uproject”
-WaitMutex -FromMsBuild” exited with code 6.

1>Done building project “CodeJunk.vcxproj” – FAILED.

Compiler can’t find definition for function void ATeddBallSpawner::StartSpawnTimer().
Either it’s missing completely or you changed parameters\return type in cpp without doing corresponding changes in header.

There can be a lot more possible reasons, but for the start you should check the most trivials