+h2(#main). development main (as of 2023-04-18)
+
+"previous: Upgrading to 2.6.1":#v2_6_1
+
+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.
+
+h2(#v2_6_1). v2.6.1 (2023-04-17)
+
+"previous: Upgrading to 2.6.0":#v2_6_0
+
+h3. Performance improvement for permission row de-duplication migration
+
+The migration which de-duplicates permission links has been optimized. We recommend upgrading from 2.5.0 directly to 2.6.1 in order to avoid the slow permission de-deplication migration in 2.6.0.
+
+You should still plan for the arvados-api-server package upgrade to take longer than usual due to the database schema update changing the integer id column in each table from 32-bit to 64-bit.
+
+h2(#v2_6_0). v2.6.0 (2023-04-06)