Compiler error with bad includes/missing files

The message I get is:

% MODULE_WORK_DIR = /g/Development/ThumperDev/RoverSoft/modules/PX4Firmware/Build/px4fmu-v2_APM.build//g/Development/ThumperDev/RoverSoft
make[3]: Entering directory /g/Development/ThumperDev/RoverSoft/modules/PX4Firmware/Build/px4fmu-v2_APM.build/g/Development/ThumperDev/RoverSoft' CXX: /g/Development/ThumperDev/RoverSoft/APMrover2/APMrover2.cpp g:/Development/ThumperDev/RoverSoft/APMrover2/APMrover2.cpp:65:23: fatal error: AP_Common.h: No such file or directory make[3]: Leaving directory/g/Development/ThumperDev/RoverSoft/modules/PX4Firmware/Build/px4fmu-v2_APM.build/g/Development/ThumperDev/RoverSoft’
compilation terminated.

It cannot find AP_Common.h and others that follow. My guess is the includes are wrong.
Where do I look for the cause?

Thanks

Was your compilation working and now its broken?
When your in the ardupilot folder you need to run
git pull --rebase
git submodule update
to ensure all your code is up to date.
Are you in the APMrover2 folder running something like
make sitl
I use sitl as the example as its the easiest to get building first. If sitl builds that’s GREAT and you can then try your px4 build with
make px4-v2

Thanks, Grant.