Change your Download Region
Try changing your Download Region to see if it affects the issue:
On Windows
1. Start Steam
2. Go to Steam > Settings > Downloads tab
3. Under Download region, select a different but relatively close region.
4. Try launching or installing the game once more
On Mac
1. Start Steam
2. Click on Steam > Preferences > Downloads tab
3. Under Download region, select a different but relatively close region.
4. Try launching or installing the game once more
Renaming ClientRegistry.blob
It's possible you may be receiving this message if Steam isn't properly configured or if configuration files are missing.
Renaming the ClientRegistry.blob will cause Steam to re-download fresh copies of required configuration files, which can solve a large number of issues.
On Windows
If the issue is isolated to a few Steam games, please exit from Steam and go to the Steamapps folder (default is C:\Program Files\Steam\Steamapps) and delete any listed .ncf files for the specific games. Once complete, please restart Steam to test the issue.
On Mac
If the issue is isolated to a few Steam games, please exit from Steam and go to the ~/Users/[username]/Library/Application Support/Steam/SteamApps and delete any listed .ncf files for the specific games. Once complete, please restart Steam to test the issue.
Connection Issues
Steam does not support connecting through a network DMZ (de-militarized zone), so this setting must be disabled in your router for Steam to function.
Many Steam issues can be caused by a firewall, anti-virus, or a problem with your router or internet connection.
Steam Network Outage
If the Steam Network is experiencing a large amount of traffic or if the network is temporarily off-line, you may not be able to use Steam immediately. Please follow the link below to check the Steam Network Status page:
Steam Network Status
Recent purchase not recognized yet
If you experience this error while trying to install or register a game, log out of Steam and log back in to determine whether or not your purchase was successfully processed:
1. Right click the Steam icon
2. Select the Settings option, then Log in as a different user...
After Steam restarts you will be prompted for your username and password. After logging in you should be able to download and/or install the games.
