I started with TB Pro backups to Dropbox and never had a problem. A couple of days ago, I decided to switch to Google Drive because I want to use all my Dropbox capacity for other things. Guess what. Same problem as above, Google drive fails midstream, repeatedly. I'm back to Dropbox and doing a backup now. No problems so far.
FWIW, I had a similar incident where I consistently couldn't complete my sync to Google Drive that turned out was because I was already almost at my full use capacity in Google Drive, Once I got rid of some files and cleaned out the Trash, I was able to again backup successfully. I have since expanded my account to give me more working space.
IMHO, TB coding for the syncs/backups is really not very robust. The notifications are pretty nondescript and there is no real logging. It seems to me that any glitch in the data transfers cause the syncs to exit, rather than execute any retries.
I've been running TB backups on as many as 4 Android devices, and consistently on 3 of them, to Google Drive and to Dropbox, so I am doing at least nine a week to each of them. In my use, I get failures here and there on each of them. I monitor the notifications and rerun manually whenever it reports an error, rather than a completion. I need to start keeping a log on which one fails the most.
The only saving grace in the error exits is that usually, the files that were uploaded prior to the exit don't have to be transfered on the subsequent manual sync, so it will make progress until all of the files are transferred. I wish things could be cleaner in this regard, but I don't think it will happen. TB has been so valuable to me, I am willing to live with this area of weakness.
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