Thanks for getting in touch! The unfortunate news is currently Octopus enforces semantic versioning for container images, where 4.8.0.Final isn’t valid semver2, and would instead have to be something like 4.8.0-Final.
We understand that this is annoying for container images, as their tags are often not SemVer. We’re currently working on relaxing this restriction in the near future, and you can track the progress of this at the following link.
A previously mentioned workaround to this restriction is “to pull that image locally, tag it (with a SemVer tag), and push it to your own repository. Essentially create a new tag pointing at the one you wish to use.”
I hope this helps, and sorry it’s not better news! Don’t hesitate to reach out if you have any further questions moving forward.