"Multiple instances of this application's installer are running. This one will stop and let another complete - 0% complete"

Hi forum users!
So, I re-installed java and re-installed Spiral Knights to refresh all the files so that I can run the game properly.
When I try to run the game I get an error message saying the following:
"Multiple instances of this application's installer are running. This one will stop and let another complete - 0% complete"
I can re-install Spiral Knights every time I want to run the game, so this is not a major issue, but any solutions would be appreciated.

Windows 10 Home
No steam
Java Version 8 Update 221
No other instances running, checked task manager, only java32 and updater opens
Haven't waited to see if the updater closes itself
If I re-install each time I want to run the game it works, if i try to launch the game again after that I get this error
Don't stress yourself too much, I'll juts check back here every now and then to see if anyone's found the solution.
Good questions though :)
Well, I surely took my time. :) I tried to download non-Steam SK client, but the installer didn't want to download anything. It finally did, so hooray!
I didn't solve the issue, but I got an idea how to go around it. You can try launching SK directly and skip the updater. At the very end of launcher.log in SK's directory is the command that launches SK. Try running it in CMD. You'll need to put all paths that contain a space between " ". Or try this shortened version:
- cd "C:\Users\YourUserName\AppData\Roaming\Spiral Knights\"
- java_vm\bin\java.exe -classpath code\config.jar;code\projectx-config.jar;code\projectx-pcode.jar;code\lwjgl.jar;code\lwjgl_util.jar;code\jinput.jar;code\jutils.jar;code\jshortcut.jar;code\commons-beanutils.jar;code\commons-digester.jar;code\commons-logging.jar -Dcom.threerings.getdown=true -Xmx256M -XX:+AggressiveOpts -XX:SoftRefLRUPolicyMSPerMB=10 -Djava.library.path=native -Dorg.lwjgl.util.NoChecks=true -Dsun.java2d.d3d=false -Dappdir=. -Dresource_dir=rsrc -Xmx512M com.threerings.projectx.client.ProjectXApp
... where the path after cd command points to your SK installation. You'll need to replace the "YourUserName" part. You can also replace "java_vm\bin\java.exe" with simply "java" to use your local installation of Java.
What brings me back to Java. What exactly do you mean by "re-install Java"? When I installed SK it also downloaded its own version of Java into the SK's directory. Whenever you launch SK, it should use this version of Java (the one it downloaded for itself) instead of the one you installed on your computer. Does your SK installer download Java, too (into java_vm folder in SK's directory) and do you do something to make it use your version of Java? Because if not, you're probably reinstalling Java for no reason. (This probably has nothing to do with the problem itself, it can just save you a bit of work.)
So, I still have no clue how to fix the updater. Another thing you can try is to check the launcher.log file if there's something suspicious. I can copy here mine log file if you want to compare it with yours. I don't know yet how well the non-Steam SK runs for me, but I suppose the difference between it and the Steam version is negligible.
Hello!
I doubt I will be of any help because I have no idea what may be causing the issue and I have never experienced it myself. But still, I'm a bit curious about this.
First off, what operating system are you running the game on? And do you use Steam? Probably not since you're also reinstalling Java. What Java version do you use to run the game? Have you performed some tweaks to SK?
I presume you checked there really aren't other instances running (even in task manager) and the error message is simply wrong. Does the updater close itself afterwards? The message implies it does. Do you get this error every time after the first launch, even when you open SK just after you boot up your computer? Do you need to reinstall both Java and SK to make it work? Isn't only one of them enough?