Octopus Server and Tentacle rely on the host OS for the available TLS version to use when establishing a secure TLS connection when communicating.
The TLS implementation uses the .NET SslStream class, and uses the best available of TLS 1.2, TLS 1.1 or TLS 1.0. Fallback to SSL is disallowed.
So it could also be that the Octopus Server has been configured to not allow TLSv1 however I’d also like to confirm if the certificate Octopus Server is using is SHA1 or SHA256?
Feel free to reach out if you have any questions or have any additional details about your process for configuring the certificate!
Could you please confirm which version of the Tentacle Docker image you are using and if you’ve made any other modifications to the image besides adding the certificate?
It might require explicitly setting the openssl system_default_sect setting to explicitly exclude protocols:
I’m not sure why the windows tentacle wouldn’t work and throw an object reference error.
Would you be able to send over Octopus Server logs from around the time you tried to register the tentacle? It may provide us more information about what went wrong there.
If you don’t mind sending over server logs, please feel free to upload them to our secure file upload.
For any customer following this thread @douchet.pantoine was kind enough to post the fix for this in this post here so head on over there to see what they did to fix it.