How to Fix KSP “Failed with Exit Code: Processing_Error”

If you’re an avid space explorer in Kerbal Space Program (KSP), you might eventually run into the frustrating error: “Failed with Exit Code: Processing_Error”. This error often appears when trying to launch the game through a mod manager or via Steam and can be quite cryptic. Fortunately, there are several proven ways to troubleshoot and fix this issue so you can get back to building your dream rockets and exploring the stars.

TL;DR

The “Failed with Exit Code: Processing_Error” in KSP typically stems from corrupted game files, problematic mods, Java runtime issues (for modded installs), or incompatible hardware settings. Start by verifying game files, updating your drivers, reviewing installed mods, and checking your system for compatibility. Most fixes are straightforward and don’t involve modifying core game files manually.

What Triggers the “Exit Code: Processing_Error” in KSP?

This error generally points to a failure in launching or initializing the game environment. There are several common culprits:

Corrupted or missing game files – Often caused by failed updates or disk issues.
Outdated or bloated mods – Incompatible mods can completely halt game startup.
Incorrect Java installation – If you’re using mod loaders like CKAN that depend on Java, the wrong settings might trigger this error.
Conflicts with graphics drivers or runtime components – Particularly after system or GPU driver updates.

Understanding which of these factors applies in your case will determine your solution pathway. Below, we’ll break down different methods to fix this problem efficiently.

Step 1: Verify Integrity of Game Files

This is the most recommended starting point, especially for users running KSP via Steam:

Open your Steam library.
Right-click on Kerbal Space Program and select Properties.
Navigate to the Installed Files tab (formerly called Local Files).
Click on Verify integrity of game files.

This forces Steam to scan and redownload any missing or corrupted files. The process can take a few minutes but often resolves the issue without further action.

Step 2: Isolate Mods Temporarily

Modding is one of the joys of KSP, but it’s also a common source of trouble. If you’ve recently installed or updated mods and are now seeing the Processing_Error, try this:

Navigate to your Kerbal Space Program/GameData folder.
Cut all mod folders except Squad (the official content) and paste them into a temporary folder on your desktop.
Launch the game.

If the game starts without the error, you’ve confirmed that one or more mods are the issue. You can then reintroduce them one by one to identify the culprit. Removing outdated or poorly maintained mods often fixes the problem permanently.

Step 3: Update Graphics Drivers and System Components

Another common source of this exit code is system-level mismatches, especially after OS or driver updates. Be sure to:

Install the latest GPU driver from NVIDIA, AMD, or Intel depending on your hardware.
Ensure DirectX, C++ Redistributables, and .NET Framework are all current.
Use utilities like Driver Booster or Snappy Driver Installer carefully to check for missing components.

Outdated or missing graphical libraries can trigger errors during the launch phase, especially with how Unity (the engine behind KSP) handles rendering pipelines.

Step 4: Check Java Installation (For Mod-Heavy or CKAN Users)

If you’re using CKAN (Comprehensive Kerbal Archive Network) to manage mods, it may require Java, especially if used with older mod frameworks or scripts.

Follow these steps to ensure proper Java installation:

Download the latest LTS version of Java from the official Java website.
Make sure to install both the x86 and x64 versions if you’re not sure what the game or CKAN uses.
Add the Java bin folder to your system’s PATH variable so CKAN can recognize and utilize it.

Mismatched Java versions or installations missing from your system registry will often result in the “Processing_Error” showing up, especially if mods are trying to execute Java-based plugins during launch.

Step 5: Adjust System Settings

Some power settings, antivirus programs, or background apps may interfere with KSP’s launch process. Try the following:

Run KSP as Administrator – Right-click your KSP shortcut and choose Run as Administrator.
Disable Antivirus Temporarily – Some antivirus software blocks mod loaders and resource packs.
Switch to High-Performance Mode – Under Windows power settings, choose High Performance instead of Balanced.

For laptops or systems with dual GPUs, ensure the game is using your dedicated graphics hardware, not integrated graphics, which may cause launch issues.

Step 6: Clean Installation (Last Resort)

If none of the above solutions work, a clean reinstall might be your best (and only) option:

Backup your GameData and Saves folders.
Uninstall KSP completely via Steam or the launcher.
Manually delete any leftover folders in your steamapps/common directory to ensure full cleanup.
Reinstall the game and reintroduce only stable mods one at a time.

While tedious, this method guarantees a clean slate. Many users report that previously persistent errors vanish after reinstalling the game with a cleaned mod palette.

Additional Tips and Community Tools

Here are some extra resources and tools that can help in diagnosing and fixing stubborn errors:

KSP Official Forums – A vast community of modders and players facing similar problems.
CKAN GitHub Issues – If you’re using CKAN, this is where others report and solve bugs.
Player Logs – Check the KSP.log file located in your root install directory for detailed error reporting.

Conclusion

While the “Failed with Exit Code: Processing_Error” message in KSP can be daunting, it’s typically tied to mod issues, corrupted files, or system incompatibilities—all of which can be fixed with some systematic troubleshooting. Whether you play stock or fully modded, following the steps above will usually get you back into low Kerbin orbit in no time. Happy launching!