What happens if you install a game to an external drive and then remove it? Does the game just not work if you try to start it? Does it get "uninstalled" according to Steam? Does Steam have serious problems? What if you plug it back in later? Does it work easily, or does it take a lot of work?

4 Answers 4


Short Answer

  1. Install game on external
  2. Unplug external > error (missing executable)
  3. Plug in external > game works
  4. Unplug external and restart Steam > game offers & requires installation
  5. Plug in external > game offers & requires installation
  6. Restart Steam > game works

Installing to the same directory when it offers & requires installation detects the game and the game will work.

Answer in Greater Detail

I installed VVVVVV on an external hard drive. The game played fine. I unplugged the drive and got this error:

Steam Error - Failed to start game (missing executable).

(Unionhawk's image)

I plugged the external drive in again and the game worked fine again.

Then, I unplugged the external drive and restarted Steam. The game was listed as uninstalled. After plugging in the external drive, the game remained as uninstalled, and launching it would prompt installation (in addition to creating a new Steam library on the external drive). Installing to the same directory at this point immediately installs the game and it starts working again.

Restarting Steam also detected the game again and it played fine.

  • What Id like to know is: What happens when I reached point 5, press "install" (because I think it's an update and I didn't recognize the HDD is unplugged), then abort the installation and re-plugin the hdd? Steam does NOT detect the game being installed in the now plugged-in HDD... the installation will continue which was started in point 5 :x
    – tim
    Mar 13, 2016 at 7:11
  • @tim the behavior might have changed since I wrote this answer, but my other answer here might help with the last steps.
    – 3ventic
    Mar 13, 2016 at 15:16
  • Yes it did - I quitted Steam (to cancel the Download of the "Update"), then deleted the Download folder within "C:\Program Files\Steam" renamed the SteamLibrary on my removable HDD to SteamLibrary2, restarted Steam and then added the SteamLibrary from the external drive. It worked, the download was aborted by me and by manually deleting and re-adding the SteamLibrary placed on the external Drive the Game was re-detected :-)
    – tim
    Mar 13, 2016 at 16:06

I like to answer every question that I can reasonably test exactly in that fashion; by reasonably testing them. So let the science begin.

I installed Super Meat Boy on a flash drive for this test. Normally, you would probably use an external hard drive, but the principle is the same. The game runs well, and I played a couple of levels, to see if saves would be affected.

I safely removed the drive and attempted to run Super Meat Boy again, and it gave me the following popup:

Failed to start game (missing executable).

It still gives me the option to play by default though, and upon plugging the drive back in, I can play without any issue, saves are retained, and stored on the drive.

  • 2
    A flash drive and a mechanical hard drive are indistinguishable from one another as far as the file system is concerned.
    – CyberSkull
    Aug 7, 2013 at 22:25
  • @CyberSkull: I get an error if I try to install a game on a flash drive, although that apparently isn't universal. Aug 7, 2013 at 22:36

I didn't install my games to a removable drive, but I did install them onto another partition. Instead of unmounting the partition though I simply renamed the folder in that partition which I designated as my Steam library. What happens then is that the folder no longer appear in my list of Steam libraries, and the games themselves appear to not be installed.

Restoring the original folder name is enough to have Steam recognize my games again as long as I don't modify any files inside it unnecessarily.

  • 1
    I was closing and restarting Steam for it to stop and start recognizing games. If you do this while Steam is running then what Unionhawk describes happens instead.
    – BoltClock
    Aug 7, 2013 at 4:22
  • 2
    I imagine the drive magically changing letters (this has happened to me many times) might screw things up too then.
    – Unionhawk
    Aug 7, 2013 at 4:39

steam just can't find the game when it attempts to start it up. when you click on the game in steam it's like a shortcut and if the shortcut is to a place that isn't on the computer at the time of pressing it it can't open it and steam will tell you just that.

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