I think it's just because when you close it by the 'X' which is what you would do without even thinking about it because well that's how it works most of the time, BA is still running, then when you try and run it again you get the error because it is already running, closing it by Options/Quit solves that problem because it actually closes it. I guess they could make the 'X' actually close the app as well as, and just like 'Quit', and make the minimize (-) button place it in the tray for those who wanted it running but out of the way, that may save the confusion/problem, probably other ways to achieve it. I don't think it will have any effect on your updating though.   

I think that "X" is misleading, so it should be changed to "_" or something.

I think it is a simple thing that Bandlab techies could redo

HIBI
I think that "X" is misleading, so it should be changed to "_" or something.

igiwigi
I think it is a simple thing that Bandlab techies could redo

Totally agree. I remember the first few times I hit the X to exit the app and I noticed it was still running in Task manager.
I had to click on quit to make it go away. Seems a little misleading to me.

I'll be darn.  I have been getting the exact same thing.  Thought it was just my computer.  Guess I better pay attention to how I close the Assistant, too.  Interesting.

Unfortunately a bunch of software doesn’t actually ‘shut down’ completely when hitting the X in the upper right GUI. The conference software Zoom is one of them. BandLab another.

I'm having the same issue even after closing the app properly.

Yep I too had the Java blah blah issues logging in with Bandlab Assistant, but I just mouse clicked my way thru it and logged back in with my Gmail/Google Account.
 
I've always had problems with BA. The reason I believe is because I use MS Edge as default system browser, which works great for me for EVERYTHING on the Internet, with the exception of Bandlab.com, which only seems to work well for me with Google Chrome.
 Bandlab is the ONLY reason I have Chrome installed on my system, simply because it makes Bandlab enormously FUN and inspiring to be a part of, being so ridiculously easy to jam and collaborate with other like minded musicians, no matter what their skill levels, or what DAW they use!
 And being able to collaborate and upload/download, mix, and edit song projects of up to 12 individual tracks at a time with anyone from anywhere is just too "bleeping" COOL! 
 And what's just as cool, you do NOT need the Bandlab Assistant to use Bandlab itself.
 However I believe you need the BA to update CbB DAW, and it has worked flawlessly with Edge for me for updating
 
 I firmly believe that being Edge is so tightly integrated into Windows 10, it is a major player as part of the OS itself and vitally important to use as the default browser to insure the smoothest trouble free updates and upgrades for Windows as well as all other software installed on my computer.
 And I don't think it's mere coincidence that everyone I know (and I mean everyone) who has problems with their computer chooses to us another browser as a default systems browser.
 
I really wish there was a way to choose browser default settings in the Bandlab Assistant FOR the BA itself so it would log in directly using Chrome, and leave Edge as my Windows default browser, but it doesn't, no big deal.
 So my one touch solution was to simply install Chrome specifically for using Bandlab.com, and simply making Bandlab my homepage for the Google browser and life is fairly simple enough to leave me some time to try and figure out how to use, understand, and navigate the Bandlab web interface. 
 It's a heck of a lot more like a cloud based version of a semi weird shotgun wedding of Apple's Garage Band to Sony's ACID then it is like the Cakewalk by Bandlab DAW itself.
 And used tandemly together with an open mind, they indeed can inspire the most fun you can have with your clothes on, or off, in or out of your own bedroom, platform, or electrical/digital communications device.
 That's right folks, you can even mix and tweak away at a multi track music project with the Bandlab "Mix Editor" from your smartphone or tablet at the laundry mat waiting for your clothes to dry. Tweak the levels, adjust panning, dynamics, reverb, etc, so on, don't forget to save your changes, and or publish your work if satisfied and you're ready to share. 

bwbalint
Unfortunately a bunch of software doesn’t actually ‘shut down’ completely when hitting the X in the upper right GUI. The conference software Zoom is one of them. BandLab another.

windows own task manager gives the best example of how this should be handled: