Tentacle upgrade task failed when going from version 3.1.5 to 3.1.6

It looks like the upgrade actually completed, but the upgrade task failed.

Task ID:        ServerTasks-3363
Task status:    Failed
Task queued:    Friday, October 30, 2015 9:23 AM
Task started:   Friday, October 30, 2015 9:23 AM
Task duration:  2 seconds
Server version: 3.1.6+Branch.master.Sha.331b6019ef669b9186a7a8ce375dd9c1ea8c14fd

                    | == Running: Upgrade Tentacles ==
09:23:43   Info     |   2 machines will be upgraded to the latest Tentacle version.
09:23:46   Error    |   At least one machine was not successfully upgraded.
                    | 
                    |   == Success: localhost-Import ==
09:23:44   Verbose  |     Octopus Deploy: Calamari version 3.1.1+Branch.master.Sha.0607d48ed0bfeed672ba23ffc568fddbae3d560d
09:23:45   Info     |     Running Tentacle version 3.1.6
09:23:45   Error    |     The given key was not present in the dictionary.
09:23:45   Verbose  |     The given key was not present in the dictionary.
                    |     System.Collections.Generic.KeyNotFoundException: The given key was not present in the dictionary.
                    |     at System.Collections.Generic.Dictionary`2.get_Item(TKey key)
                    |     at Octopus.Server.Orchestration.Health.MachineHealthResult.FromScriptResult(Machine machine, ScriptResult result) in Y:\work\refs\tags\3.1.6\source\Octopus.Server\Orchestration\Health\MachineHealthResult.cs:line 28
                    |     at Octopus.Server.Orchestration.Upgrade.UpgradeTaskController.UpgradeMachine(Machine machine) in Y:\work\refs\tags\3.1.6\source\Octopus.Server\Orchestration\Upgrade\UpgradeTaskController.cs:line 87
                    |     Octopus.Server version 3.1.6 (3.1.6+Branch.master.Sha.331b6019ef669b9186a7a8ce375dd9c1ea8c14fd)
                    |   
                    |   == Success: localhost ==
09:23:44   Verbose  |     Octopus Deploy: Calamari version 3.1.1+Branch.master.Sha.0607d48ed0bfeed672ba23ffc568fddbae3d560d
09:23:45   Info     |     Running Tentacle version 3.1.6
09:23:45   Error    |     The given key was not present in the dictionary.
09:23:45   Verbose  |     The given key was not present in the dictionary.
                    |     System.Collections.Generic.KeyNotFoundException: The given key was not present in the dictionary.
                    |     at System.Collections.Generic.Dictionary`2.get_Item(TKey key)
                    |     at Octopus.Server.Orchestration.Health.MachineHealthResult.FromScriptResult(Machine machine, ScriptResult result) in Y:\work\refs\tags\3.1.6\source\Octopus.Server\Orchestration\Health\MachineHealthResult.cs:line 28
                    |     at Octopus.Server.Orchestration.Upgrade.UpgradeTaskController.UpgradeMachine(Machine machine) in Y:\work\refs\tags\3.1.6\source\Octopus.Server\Orchestration\Upgrade\UpgradeTaskController.cs:line 87
                    |     Octopus.Server version 3.1.6 (3.1.6+Branch.master.Sha.331b6019ef669b9186a7a8ce375dd9c1ea8c14fd)
                    |   
                    |   == Failed: Summary ==
09:23:46   Info     |     OFFLINE:
09:23:46   Info     |     - localhost at https://localhost:10933/, error: The given key was not present in the dictionary.
09:23:46   Info     |     - localhost-Import at https://localhost:10933/, error: The given key was not present in the dictionary.
09:23:46   Fatal    |     One or more deployment targets were not upgraded. Please see the output log for details.

Hi,

Thanks for letting us know. Yes, the Tentacles should have been upgraded but we introduced a bug when doing the health check at the end of the upgrade. This has been fixed in 3.1.6.

Cheers
Shane