obsolete functions

Both those methods are technically internal, you should not have been using them in the first place... 😁

SetCultureInforForUserToThread, in particular, really should not be used and I can't imagine what sort of use-case one would have for that. Code should respect the choice of Culture expressed in Security, not override it.

As for GetBusinessRules, it's probably a victim of the ongoing move to Workspaces, since it assumes the old architecture. At the moment I can't say if there is an equivalent supported interface (did you try passing a Workspace ID...?); I would expect there might be ways to query the new WsAssemblyService machinery (which can be discovered from objects representing Workspaces and Maintenance Units in the public api) to fetch those, but right now I don't know the correct answer. Looking stuff up in the database is probably the safer approach for now.

If these messages are generated by supported Marketplace Solutions, they will be addressed in future releases. As sameburn mentioned, there is documentation on which solutions are actually compatible with v8.

The last message, as RobbSalzmann said, is just a compilation issue. Robb himself addressed it in this thread: https://community.onestreamsoftware.com/t5/Rules/Referencing-C-Workspace-Assemblies-from-VB-Net-Warning-Access-of/m-p/26477