Hi Nicholas,
I modified the configuration to get something in the logs. I joined a zip file containing 2 screen captures and one compressed logs file. You'll find everything you need I think.
This being said, I must tell you that after a first try, from the logs scanned by ALICE, I got this error message:
Post-processing engine and archive part size
Warning
A post-processing engine is found, but no part size is set; this could lead to timeout issues
Set a part size inside backup profile configuration.
So I just modify the Part size to ~100MB and gave another try to get that error message:
Upload cannot be initialised. Amazon S3 returned an error message: 0 :: Akeeba\Engine\Postproc\Connector\S3v4\Connector::startMultipart(): [0] The request signature we calculated does not match the signature you provided. Check your key and signing method.
Failed to process file /administrator/components/com_akeeba/backup/site-model.xxx.com-20150930-152329.jpa
Post-processing interrupted -- no more files will be transferred
Strange message that does not seem to be related to the problem.
Then I made many other tries and finally with a part size of 5 MB, it works.
I don't understand why it works with 2GB part size with version 4.3.1 on another site that is on the same server. This server is running on a full gigabit network, ssd drives, 8 cores and 24 Gigs of ram.
So for now I don't care to disable multipart uploads. My backups are not so big (500 MB to 1 Gig).
But if you can tell me what is going wrong with this, I would appreciate.
Thanks!