Check external application preferences error

Questions & Answers
1

Hi ! After I open Unity and try to open any script I have this error :

Unable to open Assets/xxx/xxx.cs: Check external application preferences
2

I believe this means that your operating system doesn’t know which application to open that file type with. Unity is trying to open it, but the operating system is gumming up the works.

I got this exact error when I loaded the official Mechanim Tutorial files (for a .fbx file). I figure the problem was that I’d just installed Maya2014, and Windows7 wasn’t associating .fbx files with Maya anymore.

So I opened the Asset folder in Windows Explorer. right clicked the .fbx file and chose “Open with…” and browsed to the Maya 2014 folder. (and then the error msg went away after I restarted Unity3D.)
(… the Robot.fbx file just opens as a raw mesh in Maya2014. which I assume is some other problem).

  • For a .cs file, I assume you need to tell windows to open that file type with MonoDevelop (or whatever you’re using to edit code).
3

Maybe you don’t have MonoDevelop installed correctly.

Try reinstalling or go to Edit>Preferences>External Tools in the Unity Editor, click on the “External Script Editor” menu and select “Browse…”. Search for “MonoDevelop.exe” (usually in Wherever-You-Installed-The-Editor/Unity/MonoDevelop/bin) and open it. I think it should work with any other Script Editor you may have.

In case of other types of assets (like animations or meshes) I assume you must set an application that can open its filename extension directly from the OS (like “Open with>Choose Default Program…” and ticking "Always use the selected program to open this kind of file"on Windows).

Hope this helps someone!

4

I had the same problem. I found the solution thanks to the other answers. The main reason that cause the error is because I am a begginer in unity and I did not know how to add a new script. I tried to add new component under Inspector while I had selected a shpere object. Then I tried to double click the script to open it through VisualStudio-or Monodevelop for you. That was a wrong way to do it.

The answer is that the script has to be in the assets of the project.

  • Click assets , add new , add a script
    in prefered language , then drag it
    in inspector components.

I was able to open the script thatway.

5

I clicked the “Override for PC, Mac & Linux Standalone” option and pressed “Apply” to fix it, But that was for a texture.

6

@N1RU actually Such a shame I didn’t know it back then, maybe then I would not need to redo all my scrips in searching for the issue :smiley:

7

I had the same error. In my case I didnt have any source editor in the Edit-Preferences-External tools - External script editor list. I tried to install visual studio separately but installer wasnt finished , just disappeared. then I found it was because Windows 7 needed some updates (see here Developer Community )

8

uhh hello I have similar issue but about fonts. I downloaded some fonts to asset folder but can’t use the because of this external application error. Anybody got a idea ?

9

same things happening to me once it said which app u wanna u for script and i chose wrong app and clicked always instead of just once so i tryed reinstalling unity and it didnt work