Received response code '400 Bad Request' while trying to upload a file chunk.
95% of the time this is because of a problem on with your connection being too slow and timing out.
Thanks for your suggestion. Reducing the chunk size didn't help, and honestly, I don't think my connection is the problem here. In the log entries below you see that backups run smoothly and transfer rather fast to my Google Drive. However, the last chunk seems to break the transmission. This is 100% repeatable and happens for whatever parameter settings (chunk sizes, timeouts, etc.).
Another thing that's bugging me and that might be related is that Backup doesn't respect the number of backups to keep locally. I've chosen 10, but older backups persist.
2012-09-25 13:11:43 NOTICE Environment: Backup 2.2; WordPress 3.4.2; PHP 5.3.2-1ubuntu4.17; SAPI apache2handler; OS Linux; ZIP 1.9.1; CURL 7.19.7; Time limit 60s; Memory limit 256M
2012-09-25 13:11:43 NOTICE Attempting to dump database.
2012-09-25 13:11:44 NOTICE The database dump was completed successfully in 0,324 seconds.
2012-09-25 13:11:44 NOTICE Attempting to create archive 'XXXXXXXXX-xxxxxx.zip'.
2012-09-25 13:11:47 NOTICE Successfully archived 1.538 files in 3,674 seconds. Archive file size is 30,98 MB.
2012-09-25 13:11:48 NOTICE Attempting to upload archive to Google Drive.
2012-09-25 13:11:48 NOTICE Uploading file with title 'XXXXXXXXX (xxxxxx)'.
2012-09-25 13:13:05 ERROR Received response code '400 Bad Request' while trying to upload a file chunk.
2012-09-25 13:13:05 WARNING The upload process timed out but can be resumed. Managed to upload 98.45% of the file. The upload speed was 412 kB/s.