I have Notepad++ portable "installed" and if I try to open a file from Windows Explorer that should open with Notepadd++ portable I get the error

Another instance of Notepad++ is already running. Please close other instances of Notepad++ before launching Notepad++ portable.

My problem is I don't want to open a separate instance, I want the file to open with the existing instance.

I found a blog post on how to get around this issue by opening multiple instances http://mattrefghi.com/blog/2010/11/how-to-launch-multiple-instances-of-notepad/ but like I said, I'd prefer the file to open in my currently running Notepad++ window

I am able to drag & drop the file in the existing window and it works, but double clicking won't open the file.

Anyone know a trick to make this work?

  • Frankly I'm surprised you can even open one instance by double-clicking with a portable version of an application (because that usually requires registry settings to associate the file extension with a particular application). – martineau Aug 16 '12 at 17:14
  • Since NotePad++ is normally single instance, your problem probably has something to do with the technique whatever it is you're using to make it portable utilizes. Seems like you could manually open the second file by using the running instance's File | Open command (Ctrl-O?). – martineau Aug 16 '12 at 17:25
  • By just right clicking txt,csv,xml files and selecting open with and then browsing to my portable np++ folder they seem to work just fine. It just won't open new files once it's already open unless i use ctrl-o or drag and drop the file. – rothgar Aug 16 '12 at 20:43

I have seen this issue happen when Notepad++ crashes when it is closed. Although the application window appears to close, the Notepad++ process is still running. You can check the task manager and kill it off from there.

This is usually caused by a plugin. You can move or rename the plugin directory and see if Notepad++ closes cleanly. If it does then add the plugins back one at a time to identify the misbehaving one.

  • I went through and cleaned up my plugins but my problem wasn't a residual running instance of np++ but rather an active copy that would not open the file in a new tab. This didn't solve the problem though. – rothgar Aug 16 '12 at 20:42

You need to point to the application executable, not to the launcher. If you point to :


it doens't work and tells you Notepad++ is already running.

But if you point to :


then everything works as expected.


This may help. You may change the default program to make sure it always open in portable NPP++. See this


I also like portable apps and setups. I use Liberkey for that. It has a portable file association app that can do the default program without writing to system registry I guess. You may also use portable apps for the same.

  • This is actually how I have it set up and it is causing the error. – rothgar Aug 16 '12 at 18:42
  • Setting to default program for an extension to a portable app seems like and oxymoron -- the whole point of one being that using it does not change the system configuration and therefore leave a trace. – martineau Aug 17 '12 at 1:35
  • @martineau see my edits. – Stat-R Aug 17 '12 at 2:09

I had the same problem, then I updated my portable Notepad++ to 6.3 Rev 2.

It works just fine now.


I had the same problem. In my case 2 installations of notepad ++ were on the harddisk. The portable version was used based on file association, the installed one was pinned to the task bar. When the portable version detected, that the installed one was running already I got that message. Hope that helps...


The notepad++ settings for Preferences - Multi-Instance set to Open Session in a new instance of Notepad++ seems to solve this problem for me.

Edit The problem was also the default setup I had for txt files - right click on the file you want to open in an already existing instance of Notepad++ and check if it is using the correct program to open the file.

In my case, I had two 1. Notepad++: A free (GNU) source code editor 2. Notepad++ Portable (PortableApps.com Launcher)

Choosing 1 opened the txt file in the existing instance of Notepad++ if the settings in Preferences - Multi-Instance was set to Default(Mono-Instance)

Choosing 2 cause the error pop-up "Another instance of Notepad++ is already running ....."

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