Casper Admin 9.73 in El Capitan "An exception of class NilObjectException

You need Casper 9.81 for OS X 10.11 support.

I'm not supporting OS X 10.11 yet, nor have I installed 9.8 JSS yet. I am simply trying to open Casper Admin from my MBAir and MacPro that I have updated to El Capitan.

You still need 9.81 for that I believe.

And apparently to run Casper Admin 9.8 from El Capitan you need to have 9.8 JSS installed. So I will have to go back to one of my other computers still running Lion thru Mavericks with 9.73 Casper Admin to manage 9.73 JSS and clients until we move to JSS 9.8 and move all clients to 9.8. Not glad I updated to El Capitan on my laptop and MacPro at this point.

You just need to get Casper Admin for 9.8.1 and it works fine. You don't have to upgrade the JSS.

@rcarey912 how are you able to get Casper Admin 9.81 to startup when the JSS is on version 9.73? I'm seeing the same splash screen as posted by @rfreeborn and it just exits the program after you click Ok. It would be great to be able to access Casper Admin from my test El Capitan system.

It works for me...

hmm, that's interesting. I wonder what could be preventing it from starting up on my system. Very odd. @rfreeborn are you able to get the Casper Admin 9.81 to startup on a El Capitan system with your JSS version at 9.73?

Nope I am still getting the Version Mismatch error.

Just to add some confirmation, I can also get the Version mismatch error here running Casper Admin 9.81 on a 10.11 Mac trying to connect to our production 9.73 JSS. It does not work. I don't know how @rcarey912 is getting it to work, assuming it actually is, but it doesn't seem to work generally speaking.
Not that I'm surprised. I believe its always been this way. You need to have the same version of server and apps.

Just to clarify, We have been running Casper Admin 9.73 on Yosemite, Mavericks, Mt. Lion and Lion computers managing our 9.73 JSS for some time. It has only now become issue running Casper Admin 9.73 or 9.81 Casper Admin on the computers we have installed El Capitan on.

@rcarey912 that does not work. I get the same thing as @mpermann and @rfreeborn

I had this problem with 10.11 despite being on Casper 9.81. Overwriting the tools with updated versions gave the same. What fixed it for me was rebooting, deleting the casper suite from /Applications, then copy again from the latest suite DMG.