Running multiple versions of VASSAL/java

Tired of being stuck in downlevel version hell ? Woudl you like to easily run uplevel versions of VASSAL (yes, I’m talking to the VSQL community). Load up the utility sdk, available at Installation - SDKMAN! the Software Development Kit Manager and running it, it can download, select and/or activate the appropriate version of java that you need to run different versions of VASSAL. I run VASSAL from a Linux CLI term window, but I’m sure sdk could be configured to run in a gui environment. You can even run mutiple different versions of these programs simultaneously if you have sufficient memory, et al. You can easily write a small script to automatically select the appropriate version of java for the level of VASSAL you are wanting to run.

Just FYI.

I imagine this is mostly for Linux folks since every version of VASSAL since 3.3 has bundled its own correct version of Java on Windows & Mac. But yes, that does sound very useful in that context!

If you mean two copies of it at the same time on one computer … probably? I mean, I can already run multiple games of Paths of Glory at the same time. I think you can even connect both separately to the server and stuff? Worth a try!

I’ve never tried that particular simultaneous scenario, and I think that depends a lot on how VASSAL handles things … even
running multiple versions of VASSAL different versions show modules loaded under opposing versions, which I’ve always put
down to VASSAL weirdness …

Right, well, however the computer handles two instances of the same program; but logically and virtually, two separate instances.

I’m not surprised that trying to run 2 instances of the same version of vassal at once only lets one run.

And also, I really don’t know anything about Windows, anymore, so I can’t advise you about that.

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I don’t follow. Could you clearly state what you mean here?

This is the Module Manager which is flashing. You’re meant to run only one MM instance at a time.

For example,
I load VASSAL 3.2.17 and load the VSQL module and the VITP module. then I start VASSAL 3.5.8 and
it shows those same modules loaded, under that instance of the vassal engine. I don’t think that’s what the
correct behavior should be.

Two things:

  • Many Linux distributions will let you have several versions of Java installed at once. (I happen to have Java 8, 11, and 17 all installed on my Fedora dev system right now.) You’ll have much less hassle using your system’s package manager to have several versions of Java installed than to do it yourself. Either way, all you’d need to do is edit to point to the java executable you want to use.

  • The VSQL maintainers could solve this problem by upgrading. The longer they postpone this, the more our memory of what needs to be done to update older modules fades. Now is the best time to act. If they don’t know what to do, they can ask for advice here.

I wanted to run 2 instances of the same version at the same time, to test and see what the modules look like. But hey, if you can’t, nothing happens. Thanks

I’m only talking about the Module Manager here. You absolutely can open a module in the Player multiple times concurrently.

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Well, in windows 11 it does not let me. I can open different versions but not the same version. Sorry if I bothered, greetings.

We must be talking about different things, then. I’d like to know what steps you’re taking to see what you see.

And just to be clear, the Module Manager is the first window that pops up when you start the vassal engine, right ?
Yes, that’s what I was describing before, multiple copies of it open.

This happens to me when I try to start two instances of Vassal of the same version. If they are different versions it starts them without problem. In short, it won’t let me start 2 instances of the same version.

Right, that’s exactly what is intended to happen: You’re not supposed to be able to start two instances of the Module Manager.

The Module Manager is the window that displays the list of modules.

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But once you have the Module Manager open (from the version that you want), you can open the same Module from it multiple times – either by double-clicking a module in your library, or from the File Menu and then “Open Module”.


Yes, but if you want to run different versions of vassal simultaneously, you do get 2 module managers; they act, though as if they were one.