Key not valid for use in specified state, Error on Tentacle

One of our tentacles have stopped working.

When opening the Tentacle manager i get this error:

Key not valid for use in specified state.

at System.Security.Cryptography.ProtectedData.Unprotect(Byte[] encryptedData, Byte[] optionalEntropy, DataProtectionScope scope)
at Octopus.Shared.Configuration.FlatDictionaryKeyValueStore.Get[TData](String name, TData defaultValue, Nullable`1 protectionScope)
at Octopus.Tentacle.Configuration.TentacleConfiguration.get_TentacleCertificate()
at Octopus.Manager.Tentacle.TentacleConfiguration.TentacleManager.TentacleManagerModel.Reload(ApplicationInstanceRecord applicationInstance) in TentacleManagerModel.cs:line 139
at Octopus.Manager.Tentacle.TentacleConfiguration.TentacleManager.TentacleManagerView.b__8_0() in TentacleManagerView.xaml.cs:line 72
at System.Windows.Threading.ExceptionWrapper.InternalRealCall(Delegate callback, Object args, Int32 numArgs)
at MS.Internal.Threading.ExceptionFilterHelper.TryCatchWhen(Object source, Delegate method, Object args, Int32 numArgs, Delegate catchHandler)

The tentacle windows service is stopped and gets stopped when i try to Start or Reinstall using the tentacle manager.

The tentacle manager UI does not show the thumbprint string as it does on other servers (where the tentacles are working).
I have verified that the tentacle thumbprint is correct and that the octopus trusted server thumbprint is correct.

The tentacle is running on a Windows server 2012 R2 Standard
Octopus Server version in 4.0.6
We are not using any connections to Azure.
This have been working perfectly up until the last few days and we have not made any changes to our infrastructure or user access.


Hi, thanks for getting in touch.

This is usually the result of either copying the config from one machine to another, or changing the Windows machine key.

I think the easiest fix is just to delete the config file and reregister the tentacle.


Hello Michael

I followed your instructions and it worked perfectly.



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