Here are the most common fixes that I've seen that you should try first one at a time:

1. Navigate to: C:\Users\[your name]\Documents\My Games.
   
2. Delete the "KillingFloor2" folder.
   
3. Try playing the game now.

1. Navigate to Steam\steamapps\common\killingfloor2\Binaries\Win64.
   
2. Locate the KFGame.exe and right-click it.
   
3. Now select "Properties".
   
4. Click on the "Compatibility" tab.
   
5. If checked, uncheck "Run this program in compatibility mode".
   
6. If checked, uncheck "Run in 256 colors".
   
7. If checked, uncheck "Run in 640 x 480 screen resolution".
   
8. If checked, uncheck "Disable visual themes".
   
9. If checked, uncheck "Disable display scaling on high DPI settings".
   
10. If checked, uncheck "Run this program as an administrator".
    
11. Click "Apply" to apply changes".
    
12. Click "OK" to close the window.
    
13. Try playing the game now.

1. Disconnect any xbox, playstation, VAKOSS, DS2 or mayflash controllers. This includes usb adapters.
   
2. Try playing the game now.

1. On your taskbar, where the icons are shown, double-click the NVIDIA Settings icon.
   
2. Select "Manage 3D Settings" if it isn't already selected on the left-side navigation.
   
3. On the right-side, go to the "Program Settings" tab.
   
4. If you only see two groupings (#1 and #2), then you do not need to make any changes.
   
5. If you see three groupings (#1, #2, and a #3), then you'll want to manually add Killing Floor 2 to #1, then make it use the high performance gpu.
   
6. If you know what "dxcpl.exe" is then make sure it isn't running for KF2, otherwise skip this step.
   
7. Try playing the game now.

1. Go to your control panel for add/remove programs
   
2. Uninstall "NVIDIA Physx".
   
3. Then navigate to: \Steam\steamapps\common\killingfloor2\_CommonRedist\PhysX\9.14.0702
4. Run the Physx installer.
   
5. Try playing the game now.

1. Go to your control panel for add/remove programs.
   
2. Uninstall all versions of 2010 Microsoft C++ Redistribs.
   
3. Uninstall all versions of 2012 Microsoft C++ Redistribs.
   
4. Navigate to: Steam\steamapps\common\Steamworks Shared\ _CommonRedist\vcredist
   
5. In the 2010 folder, install the x64 version, and right-click run as admin.
   
6. In the 2012 folder, install the x64 version, and right-click run as admin.

1. Try running the KFGame.exe as an administrator.
   
2. Sometimes this will cause a hidden error to appear.
   
3. Navigate to Steam\steamapps\common\killingfloor2\Binaries\Win64.
   
4. Locate the KFGame.exe and right-click it.
   
5. Now select "Run as Administrator".
   
6. If you get an error about a missing .dll, most likely you are having Microsoft C++ Redist installing problems.
   
7. If you get an error about "0xc000007b", skip to the end of the advanced solutions and read the directions specifically for that.

1. Navigate to Steam\steamapps\common\killingfloor2
   
2. Delete the binaries folder.
   
3. Navigate to Steam\steamapps\common\killingfloor2\KFGame\BrewedPC
   
4. Delete the file: GlobalShaderCache-PC-D3D-SM4.bin
   
5. Delete the file: GlobalShaderCache-PC-D3D-SM5.bin
   
6. Go to Steam Library.
   
7. Right-click on Killing Floor 2.
   
8. Select Properties.
   
9. Go to Local Files tab.
   
10. Click the button "Verify Integrity of Game Cache...". This should take 10-15 minutes.
    
11. Try playing the game now.

If none of the common solutions worked for you then let's go ahead and eliminate some variables. Please disable your firewall and/or antivirus for the next thirty minutes. After that is done, let's force the game to launch in a dx10, windowed mode.

1. Go to your Steam Library.
   
2. Right-click on Killing Floor 2.
   
3. Select Properties.
   
4. You are on the General tab. Click on "Set Launch Options".
   
5. Type in: -windowed
   
6. Click OK.
   
7. Try playing the game now.

If you're still out of luck, then hopefully you are at least getting a bugsplat error message. The logs are sometimes pretty helpful. To find your logs:

1. Navigate to C:\Users\[your name]\Documents\My Games\KillingFloor2\KFGame\Logs.
   
2. Locate "Launch.log". This houses the most recent "crash log".

If you don't want to attempt looking through the crash log to figure out what is going on, feel free to make a new thread in the Bug Report section of the community hub.

1. Copy the contents of your "Launch.log".
   
2. Go to www.pastebin.com.
   
3. Paste into the large memo field.
   
4. Click "Generate Paste".
   
5. When it is done loading, copy the website's URL.

If you recently installed a Window's 10 update and you see an error in your logfile stating that "this application cannot be run over a remote desktop configuration." then you should do the following:

1. Change your desktop resolution.
   
2. Reboot your computer.
   
3. Change your desktop resolution back.
   
4. Try playing the game now.

If you see errors in your logfile relating to a missing nvcuda.dll, then you should do the following:

1. Navigate to C:\Windows\SysWOW64.
   
2. Locate the file "nvcuda.dll" and right-click it.
   
3. Select "Copy".
   
4. Navigate to C:\Windows\System32.
   
5. Right-click inside this folder to paste your copied file.
   
6. Try playing the game now.

If you see errors in your logfile relating to a "[file name] Serial Size Mismatch", then you should do the following:

1. Go to Steam Library.
   
2. Right-click on Killing Floor 2.
   
3. Select Properties.
   
4. Go to Local Files tab.
   
5. Click "Browse Local Files".
   
6. Perform a search for the [file name]. Do not include the file's extention when you search (omit .stg44, etc).
   
7. Once located, delete that file and close the window.
   
8. Now you're back on the Killing Floor 2 properties. Click the button "Verify Integrity of Game Cache..." This should take 10-15 minutes.
   
9. Try playing the game now.

If you see errors in your logfile relating to a "EOF [long number]/[long number]", then you should do the following:

1. Go to Steam Library.
   
2. Right-click on Killing Floor 2.
   
3. Select Properties.
   
4. Go to Local Files tab.
   
5. Click "Browse Local Files".
   
6. Navigate to the folder that houses the file.
   
7. Once located, delete that folder and close the window.
   
8. Now you're back on the Killing Floor 2 properties. Click the button "Verify Integrity of Game Cache..." This should take 10-15 minutes.
   
9. Try playing the game now.

If you see a reference to "Bad name index [numbers]" in your logfile, then you should do the following:

1. Go to Steam Library.
   
2. Right-click on Killing Floor 2.
   
3. Select Properties.
   
4. Go to Local Files tab.
   
5. Click the button "Verify Integrity of Game Cache...". This should take 10-15 minutes.
   
6. Try playing the game now.

If you see a reference to "=== Critical error: === Fatal error!" in your logfile, this usually means there is some sort of driver conflict happening. Windows 10 automatically pushes updates sometimes so your computer may have changed overnight. You should do the following:

1. Find out what NVIDIA driver version you curently have.
   
2. Find out what the newest NVIDIA driver version is.
   
3. If you are not on the newest, uninstall your current NVIDIA drivers and upgrade to the newest version.
   
4. Try playing the game now. If that doesn't work then:
   
5. Since you are on the newest GPU version, locate the oldest version available to your GPU from NVIDIA.
   
6. Uninstall your current NVIDIA drivers and downgrade to the oldest version.
   
7. Try playing the game now.

If you see a reference to "=== Critical error: === Fatal error!" in your logfile followed up with this specific set of text:

Address = 0x76ad0944 (filename not found)
Address = 0x5bf168 (filename not found)
Address = 0x5880bed0 (filename not found)
Address = 0x1 (filename not found)
Address = 0xf34bca97 (filename not found) [in D:\Windows\system32\dxgi.dll]
Address = 0xf34c2dae (filename not found) [in D:\Windows\system32\dxgi.dll]

You should do the following:

1. Please reference the known software conflicts section.

If you see something around the lines of: "Critical: appError called: Assertion failed" then the most likely culprit is your crossfire is preventing the game gathering all necessary files during startup.

1. Find out what GPU you are using.
   
2. Figure out how to disable crossfire or force use a single gpu.
   
3. Try playing the game now.

If you are crashing when clicking on menu's then it is likely you have corrupted weapon favorites for some reason. If you see errors in your logfile relating to "Adding Weapon to favorites: string_#", then you should do the following:

1. Disable Steam Game Cloud Storage for Killing Floor 2.
   
2. Turn off Wi-Fi or unplug your ethernet cable.
   
3. When you launch Killing Floor 2 it should look like everything has "reset".
   
4. Now quit your game and turn on your Wi-Fi or plug your ethernet back in.
   
5. Launch Killing Floor 2.
   
6. Minimize it and activate the steam cloud storage.
   
7. Taken from thread: https://steamproxy.net/app/232090/discussions/1/1694923613878834990/

If you are getting "0xc000007b" error when you're running your KFGame.exe as an administrator, see below:

1. Download Dependency Walker (free, google it).
   
2. Launch Dependency Walker and hit the "open" icon.
   
3. Navigate to G:\Steam\steamapps\common\killingfloor2\Binaries\Win64
   
4. Select KFGame.exe.
   
5. In the middle of the screen you'll see a column for CPU. Click it to sort all the files by it.
   
6. Right-click on a random row and select "show full file path".
   
7. Scroll either all the way up, or all the way down, looking for any files that have "x86" in the CPU column. If they are API or EXT .dlls you can skip them. You can also skip the one named nvcuda.dll. Note the filepath it is in.
   
8. Download that .dll from online. Make sure it is the x64 version. Please be careful what site you use and do a virus check on your downloaded file if necessary.
   
9. Replace the existing .dll in the appropriate folder.
   
10. Rinse and repeat. Feel free to try clicking play after each one.

The following software may or may not interfere with Killing Floor 2:

• MSI Afterburner
  
• RivaTuner: Possible solution: run in stealth mode.
  
• OneDrive: This will cause problems if you redirect / alter your My Documents path.
  
• DAEMON Tools
  
• DAEMON Tools Lite
  
• CAM Software
  
• PlayClaw
  
• Mirillis Action
  
• Dxtory: Possible solution: Go to the "Advanced" Tab in DxTory and under "Hook Option" tick the "Delay Hook" box and set a timer of around 6 seconds or more depending on when your game stops crashing. Credit to CryCel for finding it.
  
• FRAPS
  
• D3Dgear
  
• RTSS: Possible solution: Set Custom Direct 3D Support to ON.
  
• Roccat Isku software/drivers.
  
• Roccat Swarm FX software/drivers.
  
• Logitech Gaming Software version 8.82.151: Possible solution: install version 9.