Arduino 1.6.3 won't open with New iMac and New Uno

Hi all,

I'm new here. I just opened a new iMac with OS X Yosemite 10.10.2, and have an Uno with Arduino 1.6.3. I downloaded the Arduino software and copied the folder into Applications. First Terminal gave me an error saying that I needed to install Java JDK, so I did that with the latest available version. Now it is giving me the following:

"readlink: illegal option -- f
usage: readlink [-n] [file ...]
Error: Could not find or load main class

Any suggestions? I haven't been able to find anything, and I did spend about an hour looking through forums and guides. I would greatly appreciate any suggestions!

To fill in a bit more detail which JAVA version from what source?

Had similar error. Went into Arduino program and selected Tools and then Port.

The mac port looks like /dev/cu.usbmodem...

I selected that port and hit enter. A check mark appeared next to the port and then I could upload my pgm

to the arduino. You think the system would do that automatically, but it didn't for me.

This reply was meant for another post. Sorry.

To fill in a bit more detail which JAVA version from what source?

At first Terminal said that no runtime environment was found, so I just downloaded and installed the latest JRE (8u40) from the Java development website (

That didn't work (I can't remember if it was the same error message) so I downloaded the 8u40 JDK from the same website as above. Then I started getting the error message in my original post. I also tried installing an earlier version of Java from the Apple website (Download Java for OS X 2017-001) with no effect.

Any thoughts?

1.6.3 comes bundled with all java requirements in place: you don’t need to install anything else on your own.
Just unpack the zip and double click on the arduino icon. Doesn’t that work?