The following modules are missing or build with a different engine version: UE4Editor-Scidi.dll Would you like to rebuild them now?

Hello everyone, I have a problem with my unreal engine project I’m on the engine version 4.12.0 and I created a project some time ago. Yesterday I created a c ++ to put the code that was going to move my character. When I sauvegarderm, closed and reopened, it gave me this error: The following modules are missing or built with a different engine Version: Ue4Editor-Scifi.dll yould you like to rebuild em now?
When I do so, it starts the build but there is a mistake and if I do not, nothing happens. I started my project on the 4.12.0 version and I’m still on this version, I’m not the update. I worked on the script with Visual Studio 2015.
I’m on Windows 10 64bit
Unreal engine 4.12.0
Visual Studio 2015
I tried to delete files script, it not work (which is not surprised)
I tried to reinstall Visual Studio (It’s not work)
I tried the same thing with another project (Make a c ++) and I have the same problem
I tried to open another project (It works)
I tried to build the project in Visual Studio (It’s not)
Here is the error:
Running C: / Program Files (x86) / Epic Games / 4.12 / Engine / Binaries / DotNET / UnrealBuildTool.exe -projectfiles -project = “C: / Users / Antoi / onedrive / Documents / Unreal Projects / Scifi / Scifi.uproject” -game -rocket -progress
Visual C ++ toolchain 2015 Does not APPEAR to be Correctly installed. Please verify That “Common Tools for Visual C ++ 2015” was selected When Installing Visual Studio 2015.
Visual C ++ toolchain 2015 Does not APPEAR to be Correctly installed. Please verify That “Common Tools for Visual C ++ 2015” was selected When Installing Visual Studio 2015.
Discovering modules, targets and source code for project …
UnrealBuildTool Exception: ERROR: Windows SDK v8.1 must be installed in order to build this target.

Hoping someone to a solution!
thank you :slight_smile: