RayLivingston:
The problem appears to be the build is not re-building the core. I intentionally inserted syntax errors into the Print source code, and was still able to do a successful build.So, I think the question is: How do I force a rebuild of the AVR core?
Regards,
Ray L.
I have same issue. But I have only one Arduino IDE. Even if I delete print.h from AVR {installdir}/hardware/arduino/cores/arduino Serial.println compiles with no error.