[Harmon]

I have this same problem using Mac OS 10.11.1 (El Capitan) on an iMac, running calibre version 2.40.0, the new Kindle Fire HD8 running the latest OS (which I believe is 5.0, and Android File Transfer 1.0.

The problem with the solution of not running AFT is that I need AFT to put other files on my Kindle Fire, such as videos, and the only way to do that is via AFT.

It's evident that the "race" you remark on is going on for me. Sometimes I get AFT, and sometimes AFT claims there's no device attached. In the first case, calibre doesn't recognize the HD8, but in the second case, what I find is that calibre recognizes my HD8 - both the main memory and the micro SD card.

When calibre recognizes the HD8, it very slowly commences with a "job" which it cannot finish. I get the following error message, which I also get if I then try to send files to the HD8.

calibre, version 2.40.0
ERROR: Error: Error communicating with device

Failed to upload file named: driveinfo.calibre to (u'Storage device',): 2:PTP Layer error 2002: send_file_object_info(): Could not send object info.
2:Error 2002: PTP: General Error

Traceback (most recent call last):
File "site-packages/calibre/gui2/device.py", line 87, in run
File "site-packages/calibre/gui2/device.py", line 503, in _books
File "site-packages/calibre/devices/mtp/driver.py", line 208, in books
File "site-packages/calibre/devices/mtp/driver.py", line 180, in get_driveinfo
File "site-packages/calibre/devices/mtp/driver.py", line 170, in _update_drive_info
File "site-packages/calibre/devices/mtp/base.py", line 24, in synchronizer
File "site-packages/calibre/devices/mtp/unix/driver.py", line 375, in put_file
DeviceError: Failed to upload file named: driveinfo.calibre to (u'Storage device',): 2:PTP Layer error 2002: send_file_object_info(): Could not send object info.
2:Error 2002: PTP: General Error

I tried debugging, but calibre wouldn't debug - it said:

calibre, version 2.40.0
ERROR: Device already detected: A device (Fire) is already detected by calibre. If you wish to debug the detection of another device, first disconnect this device.

I get the same results even after trying three cables. I have no other USB ports available to test, but everything else I've plugged into this particular port has worked fine.

Insofar as the "race" is concerned, I can decide whether AFT or calibre wins the race by starting the one I want first. If I start calibre and then connect my HD8, calibre grabs the HD8, shows it in the menu bar, and if I open AFT, AFT says it can't find a device. Meanwhile, I can't send anything from calibre to the HD8 even though it's sitting right there in the menu bar. (When I click on the HD8 icon, I get a blank list.

If I connect AFT first, then invoke calibre, AFT opens a window in which I can see & manipulate the HD8 files, but then when calibre opens, it does not show the HD8 as being connected.

My current work around is to plug in my HD8 with calibre not running. This invokes AFT, after which I open calibre, and can drag & drop files from the calibre listing to the HD8 in the AFT window. (Note that it doesn't seem to make any difference if my HD8 is locked or not.)