ATtiny, cannot upload, java.lang.NullPointerException

Development Tools Uploading
1

I am trying to use the SpenceKonde ATTiny core to upload code to an ATTiny85. I am using an arduino Uno with the ISp sketch on it as the ISP and am trying to use "Upload using programmer". This same technique worked fine to upload code to an ATmega328p which lacked a bootloader. I have wired everything up correctly.

But when trying to upload to the ATTiny I get:

java.lang.NullPointerException
	at cc.arduino.packages.uploaders.SerialUploader.uploadUsingProgrammer(SerialUploader.java:314)
	at cc.arduino.packages.uploaders.SerialUploader.uploadUsingPreferences(SerialUploader.java:89)
	at cc.arduino.UploaderUtils.upload(UploaderUtils.java:78)
	at processing.app.SketchController.upload(SketchController.java:713)
	at processing.app.SketchController.exportApplet(SketchController.java:686)
	at processing.app.Editor$DefaultExportAppHandler.run(Editor.java:2265)
	at java.lang.Thread.run(Thread.java:748)

Searching online for that error doesn't give any clear explanations.

This error does not happen when simply trying to compile, but it does happen immediately on trying to upload. It occurs, i think, before the computer even checks that the Arduino Uno ISP is connected.

The Arduino IDE hangs for many minutes saying "Uploading..." in the cyan bar above the black terminal area. it never gets any further.

This error does not affect uploading or uploading with the programmer to atmega328p (Arduino/Genuino Uno" boards.

Please advise of the fix for this.

2

I removed the zip file installed version from the hardware subfolder of my Arduino directory and tried installing via the URL option in the preferences dialog. It now seems to be working.