I checked Notepad++ v6.6.6 from June 2014 (two years before this thread), Notepad++ v7.0 (from Sep 2016, a few months after this thread), and the most-recent Notepad++ v7.9.5 from March 2021, and all three have this feature: specifically, there is a way to turn off that dialog.

Settings > Preferences > MISC > File Status Auto-Detection, and select Disable in the drop down (or uncheck Enable’s checkbox in v6.6.6). Once that’s disabled, Notepad++ will no longer poll the filesystem, looking for either file deletions or for updates to the file, and you won’t be prompted again. With the Auto-Detection disabled, I do not see the “This file has been modified by another program” dialog, and disabling that option also eliminated the “This file … doesn’t exist anymore”, which this topic was complaining about.

SetTitleMatchMode,2
while(true){
WinGetActiveTitle,at
; wrong IfWinActive,ahk_class Notepad++,Keep this file in editor?
IfWinActive,Keep non existing file ahk_class #32770
WinClose,
WinWaitNotActive,% at
}

SetTitleMatchMode,2
while(true){
WinGetActiveTitle,at
IfWinActive,ahk_class Notepad++,Keep this file in editor?
send,n
WinWaitNotActive,% at
}

A 3 option Radio, in the settings that contains the following:

1. Ask how to treat files that have changed or are missing. (Default)
2. Don’t Ask and keep the file open. (This makes the tab icon red.)
3. Don’t ask and close the missing or changed file.

This is just an immediate idea to set people on the right track for how this can work, and can obviously have more options than the ones I listed.

For those who are stumbling onto this topic looking for a solution,
I ask you to comment here as well to at least show that this is something you would like seen changed and show support for an amazing editor.

I’m not sure why it would be hard to sort out, just don’t ask the question and keep the file.

Or probably better to make it an option to either keep the file, don’t keep the file, or ask each time.

Jim

there isn’t such feature. Unfortunately it is something which cannot be easily solved.
Not sure if this helps you but the only thing you can do is to disable file status detection.

Cheers
Claudia