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"There is another instance of Launcher Running" error

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I have been running into this Error more often recently then when the LoL Mac client had come out originally.

Basically heres the breakdown.

I will try to launch LoL.

From there the Logo will pop up for a few seconds, then a pop up (shown in the screenshot below) will pop up. It will say "There is another instance of Launcher running, do you want to terminate it?" I hit YES, and apparently it kills the launcher. Sometimes this works, other times the launcher will simply dissapear all together, there is no icon in the dock, however for some reason, my fans will still run at around 4000 RPM, much like when LoL is launched. It NEVER does it unless there is something intensive running.

I try to launch the game again, and will get the same 'Instance is running' error, and sometimes it launches, and sometimes it does not.

I think that the launcher is stuck in a limbo somehow, and its technically running, but theres no instance of it. I was wondering why lately when I shut the lid to my laptop, it keeps running hot and the fans blaring. I think this has something to do with the 'hidden' instance of the launcher. I could be wrong, but this has started since this issue has plagued me.

If you have any questions, or need more then screenshots. I will be happy to ablidge.

Also, using a

2011 Non Retina MacBook Pro
2.4 Intel Core Duo
4 GB Ram
HD Radeon 3000 384 MB

- DrDomVonDoom


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puppy match



Had a few of these pop ups these days too. I got one today.

I played earlier today, closed and log out. A few hours later, I booted the game up again, and I got that pop up.
No visible instances was seen.
After click ok, it takes about 3-4 minutes before something really happened. I was able to relaunch League without an issue.

I am using the latest iMac, and I put my machine to sleep only (manually)...so I don't have the heating and fan issue as described by OP.

Suspecting some hidden services is not closed completely at the back...
Also, this seems to happen after I get a sudden disconnect in game and a few minutes later I get reconnected automatically.
After the game, I will see a bug spat window...but everything is still running smoothly...

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Associate Software Engineer


It's possible the UserKernel is patching itself during these times. Do you see an icon on the dock with a little blue bar on the bottom? This indicates the UserKernel is self-patching. Usually this doesn't take very long but I could see it taking up to 4 minutes if your connection to our patch servers was slow for some reason.

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I know that this is for Mac Clients, but i am on windows 7 (64 bit) and this is happening to me too.

I'll close the game, open the launcher again, it'll show the "League of Legends" Logo, and then it'll not respond, after i click "Wait for it to respond" or whatever, it'll finally ask, "There is another instance of this launcher running, do you want to terminate it?", I'll click yes, and then the patcher will load and i can play. And I've always wondered why it did this.. And I've had this error back since November/December.

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Junior Member


I have had the same thing happen to me since the release of the mac beta. It happens from time to time (probably about 2 out of 3 times when I open LoL). Normally, clicking the 'ok' button causes everything to open normally (9/10ths of the time), but every now and then (the 1/10th) it stops LoL from opening.

To the best of my knowledge, when this happens I have not seen a blue bar at the bottom of the icon, but then again, I havent really been focused on that. I'll keep an eye out for it.

Personally, I always thought the problem was that, sometimes, by clicking the icon (once), LoL would try to open two instances of the LoL client,which was remedied simply by clicking the 'ok' option.

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omg it works

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Hi Im Intens1fy

Junior Member


I have been having the same problem recently, every time I close the client, this error message will pop up. Will the game eventually work again? I have reinstalled the patch around 5 times now and each time it takes upwards of an hour and it has been very frustrating. Is there a way to fix this?

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Junior Member


So for windows 7/8 I can fix this problem by going to task manager and ending the task... simply ctrl + alt + del and look for "lolpatcher 32bit" sometimes there are two of these and you need to end both tasks for the launcher to boot properly.