If you see this error after migrating from the v2 to v3 sdk change:

$s3client->deleteObjects( array(
'Bucket' => $settings['bucket'],
'Objects' => $fileKeys
) );
to:


$s3client->deleteObjects( array(
'Bucket' => $settings['bucket'],
'Delete' => array(
'Objects' => $fileKeys
)
) );

Note the new Delete array wrapping Objects. I discovered this while updating BackupBuddy.