What is this? How do I get access?
As you've given us no clue as to where this message was generated or what you were trying to access, my best guess would be that it's an archived post that is no longer publicly viewable.
It usually means that a post has been moved to a part of the forum that forum users do not have access to.
You can not and will not be granted access.
@Snowdog37 if you were attempting to access an old post of yours from November 2022 then that thread appears to have been moved as part of the forum archiving process.