I am running Arduino IDE 1.6.4.
When I try to compile a Sketch for the Pro Mini 3.3V 8MHz I get the following error:
....\pro_8MHzatmega328\core.a: No such file or directory
Could anyone please help?
You used Boards Manager to update the standard boards to version 1.6.9. That version is only compatible with 1.6.6 of the IDE and later - on earlier versions, all compiles fail with that error. Downgrade it to 1.6.8. Open board manager, select the standard AVR boards package (I forget what exactly it's named) select version 1.6.8, and click install.