The problem was that I was using Arduino for a different project and left the serial monitor open. It was interfering with uploading Otto Blocky code. Once I closed the monitor the problem went away.
Jim Desposito 49 Resident Tinkerer
Wrote my first Fortran program as a high school student in 1969. In 1975, in grad school, I set up the control panel toggle switches of a PDP-12 so could load paper tape into it to boot it so it could read mag tapes. I also did my first assembly language programming on that machine in OS/8. My research lab then acquired a Z80 microcomputer and I wrote assembly language real-time programming to run the lab. Blah blah I wrote some iPhone apps a few years ago and now I'm tinkering with 3D printing and robotics.