+h3. UseAWSS3v2Driver option removed
+
+The old "v1" S3 driver for keepstore has been removed. The new "v2" implementation, which has been the default since Arvados 2.5.0, is always used. The @Volumes.*.DriverParameters.UseAWSS3v2Driver@ configuration key is no longer recognized. If your config file uses it, remove it to avoid warning messages at startup.
+