I opened Arduino after the recent update and went to push a previously working sketch to my MKR1500NB. I got a bunch of compiler errors for the MKR core. Checked that all my libraries and board libraries were also updated, still won't compile. Changed to a blank sketch, and still get the same thing. Here's the verbose output:
C:\Users\dnear\AppData\Local\Temp\arduino\sketches\2192A00F3EBEEB93CCB9D43218D57A35/..\..\cores\arduino_samd_mkrnb1500_9f1361a83841ca4abcb3dfb66714cc25\core.a(cortex_handlers.c.o): In function `Reset_Handler':
C:\Users\dnear\AppData\Local\Arduino15\packages\arduino\hardware\samd\1.8.14\cores\arduino/cortex_handlers.c:159: undefined reference to `SystemInit'
C:\Users\dnear\AppData\Local\Arduino15\packages\arduino\hardware\samd\1.8.14\cores\arduino/cortex_handlers.c:161: undefined reference to `main'
C:\Users\dnear\AppData\Local\Temp\arduino\sketches\2192A00F3EBEEB93CCB9D43218D57A35/..\..\cores\arduino_samd_mkrnb1500_9f1361a83841ca4abcb3dfb66714cc25\core.a(cortex_handlers.c.o): In function `SysTick_Handler':
C:\Users\dnear\AppData\Local\Arduino15\packages\arduino\hardware\samd\1.8.14\cores\arduino/cortex_handlers.c:172: undefined reference to `sysTickHook'
C:\Users\dnear\AppData\Local\Arduino15\packages\arduino\hardware\samd\1.8.14\cores\arduino/cortex_handlers.c:174: undefined reference to `SysTick_DefaultHandler'
C:\Users\dnear\AppData\Local\Temp\arduino\sketches\2192A00F3EBEEB93CCB9D43218D57A35/..\..\cores\arduino_samd_mkrnb1500_9f1361a83841ca4abcb3dfb66714cc25\core.a(SERCOM.cpp.o): In function `SERCOM::initUART(SercomUartMode, SercomUartSampleRate, unsigned long)':
C:\Users\dnear\AppData\Local\Arduino15\packages\arduino\hardware\samd\1.8.14\cores\arduino/SERCOM.cpp:69: undefined reference to `SystemCoreClock'
C:\Users\dnear\AppData\Local\Temp\arduino\sketches\2192A00F3EBEEB93CCB9D43218D57A35/..\..\cores\arduino_samd_mkrnb1500_9f1361a83841ca4abcb3dfb66714cc25\core.a(Uart.cpp.o): In function `Uart::begin(unsigned long, unsigned short)':
C:\Users\dnear\AppData\Local\Arduino15\packages\arduino\hardware\samd\1.8.14\cores\arduino/Uart.cpp:50: undefined reference to `pinPeripheral'
C:\Users\dnear\AppData\Local\Arduino15\packages\arduino\hardware\samd\1.8.14\cores\arduino/Uart.cpp:51: undefined reference to `pinPeripheral'
C:\Users\dnear\AppData\Local\Arduino15\packages\arduino\hardware\samd\1.8.14\cores\arduino/Uart.cpp:55: undefined reference to `pinPeripheral'
C:\Users\dnear\AppData\Local\Arduino15\packages\arduino\hardware\samd\1.8.14\cores\arduino/Uart.cpp:60: undefined reference to `pinMode'
collect2.exe: error: ld returned 1 exit status
exit status 1
Compilation error: exit status 1