[Txxb161]

Kodi 17.6 Backup from old FireTV Box V. 1 FireOS 5.26.3 does not work , folder addons is missing,
no failure in adblink log for backup
only backup with adbLink v 3.5 is ok, 3.6 and 3.7 did not backup addons folder

v3.7 Backup is ok with FireTV Stick V2

 Thank you for the report. Unfortunately, I no longer have any gen1 AFTV devices to test with, my last died a while back.  

I suspect that the adbLink v 3.6 upgrade from adb 1.0.32 to 1.0.39 is causing your issue. You can revert back to the old adb by copying the adb binary and adb*.dll files from your v3.5 folder to the 3.7 folder. For Linux, look in the adbfiles folder, for Mac look in adbLink.app/Content/MacOS/adbfiles/. I just tested this  on a Mac and it seemed to work ok.  

 FWIW, although I do not regularly use the backup function in adbLink as I do manual backups, I just ran a backup test using adbLink v3.7 on my Gen 1 Fire TV box and verified that the entire contents of the .kodi folder were, indeed, backed up as expected, including the addons folder.