Assertion failed: Unknown platform 6 in GetTargetPlatformGraphicsAPIAvailability

I've just recently been getting two of these errors every time I start Unity. Anyone have any idea what this is?

Unity 2017.2.0f1

Not sure if it has anything to do with one scene crashing out of Unity every time without so much of an error message...

 

I have the same issue

 

I'm also getting this error and I'm not sure what it is.

I'm trying to find out if it has anything to do with this error:
https://forum.unity.com/threads/unable-to-open-unity.504938/

 

I have this and the problem is detailed in the logs:

Code (csharp):

1.  
2.  COMMAND LINE ARGUMENTS:
3. C:\Program Files\Unity2017.3\Editor\Unity.exe
4. C:/bathroomsbydesign-app2017.3
5. Loading GUID <-> Path mappings...0.000110 seconds
6. Loading Asset Database...0.057577 seconds
7. Unknown platform 6 in GetTargetPlatformGraphicsAPIAvailability
8. (Filename: C:\buildslave\unity\build\Editor/Src/BuildPipeline/BuildTargetPlatformSpecific.cpp Line: 2048)
9.  
10. Unknown platform 6 in GetTargetPlatformGraphicsAPIAvailability
11. (Filename: C:\buildslave\unity\build\Editor/Src/BuildPipeline/BuildTargetPlatformSpecific.cpp Line: 2048)
12.  

bug: 989239
Alas I have not time to provide a minimal project showing said bug