Hi,
When we use 2.8.3 client with our 3.9.2 server there are a lot of menus and options that go missing in Openfire. I know that the new 4.2.2 Openfire has the options to turn on and off parts of Spark but we don’t have that installed in 3.9.2, does the plugin even work in 3.9.2?
You have Client Control plugin installed on your server. As the older plugin’s version is installed, it replies to Spark with false about settings it doesn’t know. As Spark receives false reply it disables the settings. You can’t update the plugin, as it requires newer Openfire version. So, your options are to either remove that plugin from Openfire, update to the latest Openfire and update the plugin, use Spark 2.7.7 or older.
Sorry, i don’t understand your last message. Explain what is wrong and what you want to do.
If I use our current 2.6.3 Spark Client will it have any issues connecting to a 4.2.2 server?
I’m able to login to 4.2.2 server with Spark 2.6.3, so it seem to work, though you might run into some issues in the long run. But why do you want to update the server and keep the old version of Spark? Your first question was about missing menus in Spark 2.8.3, that was because of old Client Control plugin used on the server. If you are going to use 2.6.3, it only supports a few settings from Client Control and you shouldn’t have problems with it still using old server and old plugin. Of course, i would vote to update everything to the latest version 
My plan is to keep the old spark for the moment. Update the server first, get the settings for client control where I want them and then do a mass push of the new spark out. I was going to do the new spark first but i can’t turn off client control on the current 3.x.x server because we use pushed bookmarks etc…
I see. Well, bookmarks are now separated to Bookmarks plugin, but it requires at least 4.0.0 to work. Yeah, don’t forget to install Bookmarks plugin once you update Openfire and Client Control plugin.