avrdude not in sync on Arduion 1.6.9 running on Linux Mint 64 bit

HI,

I've been looking at similar issues that people seem to be having with various avrdude failures on 64 bit systems.

I recently upgraded my desktop to 64-bit Linux Mint 17.1 and all is going well except that I cannot upload any sketches to my UNO board(s).

Note I have tested the same UNO board and USB cable with my 32 bit installation of 1.6.9 and that doesn't appear to have any problem uploading sketches.

On the 64 bit system I get the avrdude: stk500_getsync() ... not in sync: resp=0x00 errors until it times out after 10 retries.

Here's what I've tried so far:

1 - Did the loopback test on the 64 bit system and the UNO board responds echoing what I type in the serial terminal
2 - Tested the UNO board and USB cable on my 32 bit notebook installation and that worked just fine, no errors uploading sketches.
3 - Uploaded the ASCII table sketch on the 32 bit system and then move the UNO to the 64 bit system and brought up the serial terminal in the IDE. The sketch runs and I get the ASCII table output on the 64 bit system.
4 - renamed the avrdude under the IDE install directory and created a soft link to the version installed in Linux Mint in /usr/bin. No difference in the problem.
5 - Yes, I have the UNO board selected and /dev/ttyACM0 (verified port) selected in the IDE on the 64bit system.
6 - Yes, I am a member of the dialout group.

Has anyone had exactly this type of failure, and did you ever find a solution to the problem? If there is a real solution buried in the forum that I have missed could you point me to it?

Thanks,
Burt

Another bit of detail, it appears that it is avrdude that is the issue.

I did a test from the command line and ran as sudo for good measure, but avrdude is giving the same error run with sudo.

And I also tried with the version of avrdude that is installed in /usr/bin even though I didn't expect that to make any difference due to my earlier testing with the soft link.

I guess I'll try to see if there is any useful information from the avrdude developers/users.