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Specific Error Messages

ATI and Nvidia Hardware Promotion Issues

This offer has already been activated using a different Steam account.

The offer which you are attempting to register has already been activated on your machine. Please see the Resetting a Lost Password topic for instructions to locate the account the promotion was registered to.


This Steam account already owns the product(s) contained in this offer.

The offer has already been registered to your account. If the games do not appear in your account immediately, please exit and restart Steam to confirm whether or not the registration was successfully completed.

If the games do not appear in the Library section once you have logged back in to your account, please submit a support request.

Sorry, this computer does not meet the system requirements for the offer.

The hardware promotion does not apply for your machine.

If you believe that you have received this message in error, please follow the instructions in the Checking DirectX Settings topic to generate a DXDIAG report.


Sorry! We require DirectX 9 or above to verify the eligibility requirements for the offer.

This error message indicates that the version of DirectX on your machine must be updated. Please see the Checking DirectX Settings topic for instructions to update DirectX to version 9.0c or better.


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Disk Read or Write Error


The main cause of this error is generally errors on your hard drive. These can either be bad sectors that have not yet been marked as bad by the filesystem, or your hard drive may be failing.


The first step is to verify that your hard drive is in good health and that all bad sectors have been marked as such by the drive.

To do so on Windows:

  1. Click Start > (My) Computer
  2. Locate the hard drive Steam is installed on. By default, this is C:
  3. Right-click this drive and select Properties.
  4. Click the Tools tab.
  5. In the Error-checking category, click Check now...
  6. In the dialog that appears, check "Automatically fix file system errors" and "Scan for and attempt recovery of bad sectors."
  7. Click Start.
    • If you are scanning the C: drive, you will be asked to schedule the disk check the next time you start Windows. Accept, restart your computer, and allow the disk check to start—do not press any keys to skip the disk check.
  8. Allow the disk check to complete. This process may take up to several hours, depending on the size of your hard drive and the number of errors.

To do so on OS X:

1. Open Disk Utility.
2. Select your harddrive.
3. Click First Aid and follow the prompts.

Once your hard drive has been checked, verify the integrity of the game files

Please see Verify Integrity of Game Files for instructions.

If you are still seeing this error, move your Steam installation.

We recommend testing on another hard drive, but you can also try installing Steam in another folder such as C:\Steam\

We also recommend redownloading the game instead of using your existing files—you can back up your steamapps folder in the meantime.

The reasons for doing so are multiple:

  • It ensures a fresh copy of the files are downloaded.
  • It will generally install the files to a new physical location on your hard drive, avoiding the physical location that the issues are occurring at.
  • If there is an issue with your Steam installation, or a bug with Steam, it will reset the state of your Steam installation, possibly preventing the issue from reoccurring.

Please see the article on Moving a Steam Installation and Games.

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Failed to start game (app already running)

What does "Failed to start game (app already running)" mean?

This error is most commonly seen when launching a game that has closed improperly with a silent crash, or that is failing to launch properly.

Sometimes, the game may already be running under a different user account within your operating system.


Verifying your Game Files

In some cases, this error message will appear when there is an issue with the installation of a game. Complete the instructions as they are shown in the following link:

Verifying your Game Cache Files (GCF)


General Troubleshooting

If the game is failing to launch correctly, or has silently crashed previously, you will need to contact the support team for that game to troubleshoot the crash/failure to launch.


When contacting the third-party support team for a game issue such as this, ensure that you click the blue "Problem with this game? Contact Support" button on the right side of the crashing game's Steam Support page to access the correct support site.

If you think there may be another user account on your computer that may be running this title, try logging out of all other user accounts, restarting your computer and testing the issue again.


Opting out of the current Steam beta

If you are currently participating in the Steam beta, try opting out and testing the issue again.

  1. In Steam, click on "Steam" in the upper left, then choose the "Settings" menu. (Preferences on Mac)
  2. On the "Account" tab under "Beta Participation" click the "Change..." button.
  3. Select the "NONE - Opt out of all beta programs" from the drop down list and click "OK".
  4. You will be prompted to restart Steam, please select the "Restart Steam" button.

Participants in the Steam beta programs should always test both the beta and normal versions of Steam when troubleshooting an issue.


Forcing a silently crashed/hanging game to close

For Windows computers, try the following:

  1. Press the following keys at the same time: Ctrl  Shift  Esc. This will launch the Windows Task Manager.
  2. Select the Processes tab.
  3. Find and select the game's executable file in the list. You can obtain detailed information by expanding the Description column.
  4. Right-click on the selected process.
  5. Select "End Process".
  6. If Windows asks you to confirm that you wish to quit this game, click the "End Process" button to confirm.

The game should now be closed. You can try launching the title again, or proceed to other troubleshooting options.

If this fails, or Windows is having trouble closing the game with this method, try restarting your computer.

For other operating systems, try restarting your computer. Once your computer restarts, perform any troubleshooting operations that you intend before attempting to launch the game again.

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Failed to Start Game (Missing Executable)

Troubleshooting Steps


Step 1 - Check your anti-virus software

This error is most commonly seen when your anti-virus software mistakenly reports game files as malicious and quarantines them.

There are a couple of ways to resolve this:

  • within the anti-virus software look for game files that have been reported and mark them as safe
  • set your anti-virus software to Game Mode
  • have the anti-virus software exclude that game folder when it scans for malicious content. Here's how to do that with popular anti-virus software.

You should also temporarily uninstall any applications listed in our Programs Which May Interfere with Steam.


Step 2 - Verify Game Files

If it's not caused by anti-virus software, the issue could be a corrupted file or failed download. To make sure you have all the files needed, restart your PC and then verify your game files. You can easily do that from your Steam Settings panel.


Step 3 - Submit a Steam Support ticket

If you've completed Steps 1 and 2 and are still seeing this error, please submit a ticket to Steam Support.

We'll ask you for the following, so go ahead and include them with your ticket:

Our goal is to get you playing your games, so we'll review your information and suggest additional troubleshooting steps.

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Game is not available on your current platform

Operating system compatiblity and SteamPlay

This error message means that the game is not supported on the operating system that you are currently using.  You can check each game's system requirements and compatible operating systems on that game's Steam Store page.

Games that list SteamPlay on their Steam Store page can be played on any of the two or more operating systems that are listed next to the SteamPlay icon.



When checking system compatibility with a specific game, ensure that you check the game's hardware requirements in addtion to compatible operating systems.



Most Steam games can be played on a supported Windows operating system. Ensure that you check which versions of Windows are supported for any game that you are interested in purchasing. Most games that support Windows 7 will also work with Windows 8.



A list of featured Mac OSX games can be found here:

You can also perform a search within the Steam Store and then select "Mac" in the operating system dropdown box to filter to Mac OSX compatible results only.

Be sure to check the specific version of OSX that is required for any game that you are insterested in.


Ubuntu Linux

Steam and its games are currently only supported on Ubuntu with Unity, Gnome, or KDE desktops.

A list of featured Linux games can be found here:

You can also perform a search within the Steam Store and then select "Linux" in the operating system dropdown box to filter to Linux compatible results only.



Some users will deliberately purchase a game that is not available on their operating system with the aim of running the game with emulators or other utilities that simulate the game's system requirements. Be aware that purchases made with this goal in mind are not supported by Steam Support.

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Incomplete Installation (#) Errors

Network Connectivity Issues

Internet or other network connectivity issues are the most common cause for encountering an "Incomplete Installation" error. Please visit the Troubleshooting Network Connectivity and Required Ports for Steam articles to ensure that your network is properly configured for Steam. Common error codes for connectivity issues include 3, 16, 20, and 35.


Common Error Codes 

Incomplete Installation (2)

Many of these issues were tied to FAT32 drives which has been corrected in a Steam update.

Some users have also reported moving the Steam installation to the default C:\ Drive will correct this issue.

If the issue persists, please contact Steam Support.

Incomplete Installation (3)

Steam can not connect to the internet.  Please see the Troubleshooting Network Connectivity article.

Incomplete Installation (10)

Steam servers are busy.  Please try again later.


Incomplete Installation (16)

Network timeout.  Please wait a few minutes and then try launching the game once more.  If the issue persists, please complete this guide.

Incomplete Installation (20)

Steam servers are unreachable.  This may mean Steam is experiencing technical difficulties. It may also be that your network needs to be properly configured for Steam.

Incomplete Installation (35)

Please ensure that the Required Ports for Steam are open.


Incomplete Installation (53)

Various antivirus applications are known to interfere with Steam and cause this error.  Please try following the suggestions in the Error Code 53 article. 

Incomplete Installation (55)

This issue can also occur on computers with Avast installed. You will need to configure Avast to ignore Steam itself and all Steam game files. Some users have had to uninstall Avast to resolve the issue.

This may also indicate a Steam Service failure.  Please try enabling the Steam Service:

  • Exit Steam.
  • Click Start > Run (Windows Key + R)
  • Type the following command:

    C:\Program Files (x86)\Steam\bin\Steamservice.exe /Install 

    (If you have installed Steam to another path, please replace C:\Program Files (x86)\Steam with the correct path.)

    This command requires administrator privileges and may take a few minutes.
  • Launch Steam and test the issue again. 

McAfee Security Scan is also known to create this error for Left 4 Dead 2. 

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Steam is already running

This error message indicates that Steam is not loading properly. The process is running in the background and is visible in Task Manager's Processes tab, but is not launching the user interface.

Compatibility Mode

Please ensure that Steam is not set to use Compatibility features:

  1. Browse to your Steam installation (Usually C:\Program Files\Steam\)
  2. Right click on Steam.exe, choose Properties.
  3. Click on the Compatibility tab.
  4. Uncheck any boxes that are checked, and click Apply.
  5. Then, click the "Show settings for all users" button.
  6. Again, make sure none of these boxes are checked, and click Ok.
  7. Click Ok to close any open dialog boxes.


Reinstall Steam

If Compatibility features were not inabled, or if disabling them fails to resolve the issue, your Steam installation may be corrupted. Pease follow the instructions below to reinstall Steam files without affecting your installed games:

  1. Exit Steam and go to the folder called C:\Program Files\Steam\ (this is the default location for a Steam installation - if you set a different installation directory, you will need to browse to it).
  2. Delete all of the files in this folder except:
    • The Steamapps folder and Steam.exe (If 'exe' is not visible, look for the black and white Steam icon)
  3. Restart your computer.
  4. Then, you will need to launch Steam.exe from within the Steam installation folder, and not from a pre-existing shortcut.


Interfering Applications and Malware

To test if there are interfering applications, please review the information provided in Programs Which May Interfere with Steam.

In some cases, malware may be to blame for this issue. Please ensure your computer is free from any possibly malicious software.

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Steam is no longer supported on this computer's operating system

Microsoft has ceased development for Windows 98 and Windows ME. Steam includes features that these operating systems can not support.

In order to continue using Steam, you must upgrade your operating system to a more recent version of Windows.


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The Steam Browser is Disabled


The Steam Web Browser requires a CPU that supports the SSE2 instruction set. Intel added support for SSE2 instructions in the Pentium 4 (c.2001), and AMD added these instructions in c. 2003 Opteron and Athlon 64 processors.

If your CPU or computer lacks the SSE2 system requirement, you will need to view Steam-related web content in your default web browser.

We recommend upgrading your computer with a CPU that has SSE2 support if you would like to use the Steam Client web browser.


32-bit Linux distributions are also no longer supported. Please install a 64-bit Linux distribution to make use of the Steam browser.

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This game is currently unavailable

Windows Troubleshooting Steps

After each step, please re-test the issue.

  1. Exit and restart Steam
  2. Update All Drivers - including DirectX, PhysX, and Visual C++ as found at the bottom of the guide
  3. Exit Steam and delete everything under the Steam installation directory except Steam.exe and the \SteamApps folder - this will force Steam to update when you log in
  4. Complete the Verifying GCF Cache Files process to repair your game cache files.
  5. This error may be caused by having certain Steam files set to Read Only. To resolve this:
    • Exit Steam.
    • Navigate to the directory where you have installed Steam. (Typically C:\Program Files\ or C:\Program Files\Valve\.)
    • Right-click on the Steam folder.
    • Select Properties.
    • Check the Read-Only checkbox and press Apply.
    • Uncheck the Read-Only checkbox and press Apply.
  6. If this issue is only happening on a third party non-Valve game, please try launching the game's .exe directly from its installation folder: C:\Program Files\Steam\SteamApps\Common\<Game Title>.  You may also try other .exe's such as Launcher.exe in the game folder to see if a different error message is found.
  7. If the issue persists, it may be caused by a network configuration issue.  Please complete the Troubleshooting Network Connectivity guide to further assess the problem.


Data Execution Prevention

  1. Go to Start > Control Panel > System > Advanced > Performance > Data Execution Prevention.
  2. Select "Turn on DEP for all programs and services except those I select:"
  3. Select "Add", navigate to C:\Program Files\Steam (or your default Steam directory), and add Steam.exe to the exception list.
  4. Additionally, you will want to add any .exe's for the game you are seeing issues with.  These files will either be in Steam\steamapps\common\<Game Title> or in \Steam\steamapps\<Your Steam Account Name>\<Game Title>\


Mac OS X Troubleshooting Steps

After each step, please re-test the issue.

  1. Exit and restart Steam
  2. Make sure your Mac is fully updated
  3. Exit Steam and delete everything except SteamApps under the Steam installation directory, ~/Users/[username]/Library/Application Support/Steam, this will force Steam to update when you log in
  4. Complete the Verifying GCF Cache Files process to repair your game cache files.
  5. If the issue persists, it may be caused by a network configuration issue.  Please complete the Troubleshooting Network Connectivity guide to further assess the problem.


Secondary Installers

Many Steam games include installers for features and services required by the game. These include installers for DirectX, PhysX, Games for Windows Live, C++ components, or Windows updates required by the game.

Steam is designed to run these installers when the game is first launched. If an installer is canceled by a user or prevented from running by another application on your system, the game may not launch correctly.  If this occurs, these installers will need to be launched manually.

These installers are found in the game's installation folder, or a subfolder, found in the following location by default:

C:\Program Files\Steam\steamapps\common\<Game Title>\

Note: Your installation path may differ from the above location.

Third Party Games

In some cases, this issue can be resolved by installing or reinstalling the Microsoft Visual C++ 2008 Redistributable Package.  These installers can be found at the bottom of this guide.

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Update & Installation Issues

Basic Steam Troubleshooting

The following fixes will resolve most update and installation errors with Steam. They can be performed with a minimal amount of technical knowledge.

Restart Computer

It's always a good first step to make sure that you restart Steam as well as your computer.

Restarting the computer flushes all kinds of system states and caches, while resetting other programs and releasing locks on files and other resources.

Clear Download Cache

Clearing the Steam download cache will cause the Steam client to flush locally cached configuration data and acquire it from the Steam servers again.

Navigate to your Steam -> Settings -> Downloads -> Clear Download Cache

Repair Library Folder

The Steam library folder contains all of your installed games on disk. These folders need to be writable by all users in order to update properly. Sometimes these user permissions break and need to be refreshed.

Navigate to your Steam -> Settings -> Downloads -> Steam Library Folders -> Right click on folder -> Repair Folder

Verify Local Files

Sometimes files on hard-disks and other storage devices become corrupted because of bad hardware, software crashes, power surges etc. Steam can verify the correctness over installed game files and fix them if necessary.

Find Game in Library -> Right click -> Properties -> Local Files -> Verify Integrity of Game Files

Change Download Region

The Steam content system is divided into geographical regions. The Steam client automatically detects its current region and uses content servers located in that region for best performance. Sometimes, servers in a specific region may be slow, overloaded or have a hardware failure causing download issues. It is advisable to temporarily switch to a different download region to use another set of content servers.

Steam -> Settings -> Downloads -> Download Region. You may need to test several regions other than your own.

Reinstall Steam

The Steam installer can be downloaded here: ( and reinstalled to the same location where it is already installed.

This may fix potential issues with Steam client and service files. Installing into same location will preserve all installed games.

WARNING! Uninstalling Steam will delete all game content.

Move Game Folder

It can be very helpful to test the issue by installing on an alternate hard drive. If one is already available, you can create a new Steam library folder on this drive. You can then install new games into this Steam library folder or move already installed games there.

Steam -> Settings -> Downloads -> Steam Library Folders -> Add new Library folder

Advanced Troubleshooting

If the error is still occurring after following the fixes outlined above, it is possible that something outside of Steam is responsible.

Because these are advanced troubleshooting steps, we highly recommend that you contact a local IT support specialist in your area for further assistance with these steps.

Refresh Local Network Hardware

This includes restarting all modems & routers. Network hardware can get into slow/broken state after running for a long time.

Update System & Drivers

Make sure your operating system and hardware drivers are all up to date.

For Windows: Start → search "update" → run "Check for Updates"

For Mac: drivers cannot be updated separately; only the operating system can be updated.

Investigate Firewalls

Certain firewalls may prevent Steam from talking to its servers. You'll want to work with a tech support specialist to ensure that the Firewall is not interfering. You may even need to temporarily disable it for testing purposes. It may be necessary to add exceptions in your firewalls for Steam.

Investigate Anti-Virus Software

AV software hooks very deep into user systems and can affect disk and network operations which will cause issues with Steam. Some games also use copy protection technology that can appear as malicious software to an AV scanner, resulting in potential false-positive alerts.

You'll want to work with a tech support specialist to ensure that your AV software is not interfering with Steam. You may even need to temporarily disable it for testing purposes. It may also be necessary to add exceptions for Steam in your AV configuration (for example, excluding Steam Library folders from live monitoring services).

Investigate Other Programs & Services

Any software that modifies or monitors system, disk or network activity can cause issues while downloading or running a game. These programs and services can run in the background and are typically associated with software like Anti-Virus, ad-blockers, web-optimizers, firewalls, system cleaners, recording software, proxies, performance boosters etc.

You'll want to work with a tech support specialist to ensure that these services & programs are not interfering with Steam. You may even need to temporarily disable them for testing purposes.

Disable Overclocking

Some users overclock their hardware to gain more performance while running their system outside of manufacturer recommended settings. This can cause memory and file corruption and should be disabled (usually in the computer BIOS).

Test Online Connection

Some Internet providers cache or compress online data to save bandwidth (especially cellphone networks). This can cause issues with Steam. It is a good idea to test the issue by connecting to an entirely different network, preferably from a different service provider.

Check Hard Drive for Errors

All storage drives/devices can be affected by file corruption, especially if it is older or running under a heavy load. You'll want to work with a tech support specialist to investigate possible issues with your Hard Drive

For Windows: My PC → Right Click on Drive → Properties → Tools → Error checking

For Mac OSX: Disk Utility → Click on Drive → Click First Aid (For older OSX versions: click Repair Disk Permissions)

Check RAM for Errors

Memory errors can cause issues with the Steam installation process, as well as gameplay. You'll want to work with a tech support specialist to investigate possible issues with your system memory.

Windows : Start -> Find "mdsched" and run Windows memory Diagnostic

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