Nucleus Co-Op Troubleshooting Guide

Having trouble with Nucleus Co-Op? This guide covers the most common issues and their solutions — from controllers not being detected to the OneDrive path error, black screens, ProtoInput failures, and performance problems.

Before Troubleshooting: Checklist

  • ✓ Your Nucleus Co-Op folder is added to Microsoft Defender exclusions.
  • ✓ You extracted NucleusApp.zip with 7-Zip using the password "nucleus".
  • ✓ Nucleus is installed at C:\NucleusCo-op — not in Program Files or a OneDrive folder.
  • ✓ You are running NucleusCoop.exe as Administrator.
  • ✓ You have Microsoft .NET Framework 4.7.2+ and Visual C++ Redistributable 2019 installed.
  • ✓ Your Windows display scale is set to 100%.
  • ✓ You have read the game setup notes for your specific game.

Nucleus Co-Op Won't Launch or Crashes on Startup

1.

Update Microsoft .NET Framework to the latest version.

2.

Reinstall Visual C++ Redistributable 2015-2019 (both x86 and x64).

3.

Add your Nucleus folder to Microsoft Defender exclusions before extracting.

4.

Extract NucleusApp.zip with 7-Zip using password nucleus — not Windows built-in extraction.

5.

Install DirectX End-User Runtime on Windows 11 if needed.

6.

Run NucleusCoop.exe as Administrator.

7.

Restart your PC and try again.

Related searches: nucleus coop not working, nucleus coop wont open, nucleus coop crashing, nucleus coop fatal error

Input Support File Missing or Input Setup Failed

1.

Microsoft Defender may have removed ProtoInputHooks64.dll as a false positive.

2.

Open Windows Security > Virus & threat protection > Protection history.

3.

Restore the blocked file or add your entire Nucleus folder to exclusions.

4.

Re-extract NucleusApp.zip with 7-Zip into the protected folder.

Related searches: nucleus coop proto input failed, ProtoInputHooks64 missing

Black Screen When Launching a Game

1.

Launch the game normally first and set it to windowed mode.

2.

Disable Discord, Nvidia GeForce Experience, and MSI Afterburner overlays.

3.

Set monitor scale to 100% in Windows Display Settings.

4.

Run Nucleus as Administrator.

5.

Verify game files in Steam.

6.

Read the game setup notes for your title.

Related searches: nucleus coop black screen, nucleus coop game not launching

Controller Not Showing Up

1.

Hold a button on the controller for 2 seconds — icons appear only after input.

2.

For PS4/PS5: run DS4Windows before Nucleus.

3.

For generic controllers: use XOutput or x360ce to emulate Xbox-style input.

4.

Do not put x360ce DLLs inside the Nucleus folder.

5.

Disable Steam Input for that game in Steam settings.

6.

Use HidHide if one controller moves both screens.

Related searches: nucleus coop controller not working, nucleus coop not detecting controller

OneDrive Error / Path Is Not Valid

1.

Sign out of OneDrive.

2.

Reset Documents to C:\Users\YourName\Documents via Properties > Location.

3.

If blocked, turn off OneDrive sync and unlink the device.

4.

As a last resort, set the Personal folder registry value to %USERPROFILE%\Documents.

Related searches: nucleus coop onedrive, nucleus coop the path is not of a legal form

One Game Window Lags Behind the Others

1.

Lower graphics settings in every instance.

2.

Cap FPS (for example 60) in each copy of the game.

3.

Press Ctrl+H in Nucleus to unfocus all windows.

4.

Enable Vsync in your GPU control panel.

5.

Close background apps using CPU or GPU.

Related searches: nucleus coop one instance lagging, nucleus coop fps low

Game Executable Not Found

1.

Use Search Game in Nucleus and browse to the game's .exe manually.

2.

Steam games are usually in C:\Program Files (x86)\Steam\steamapps\common\[GameName].

3.

Check bin or binaries subfolders for the main .exe.

4.

Remove the game's Nucleus content folder and add the game again.

5.

Verify game files in Steam.

Related searches: nucleus coop can't find exe, nucleus coop the executable was not found

Keyboard or Mouse Not Working in Game Windows

1.

Press End to lock input after instances are running.

2.

Confirm your game setup supports multiple keyboards and mice.

3.

Move the mouse or press a key so Nucleus detects the device.

4.

Disable Steam Input and close macro software.

Related searches: nucleus coop keyboard not working, nucleus coop mouse not working

Game Windows Look Stretched

1.

Set Windows display scale to 100%.

2.

Add custom resolutions in your GPU settings (e.g. 1920x540, 960x1080).

3.

Use Custom Resolution Utility if your GPU panel lacks options.

4.

Press Ctrl+R in Nucleus to resize without closing.

5.

Match resolution across monitors if using more than one.

Related searches: nucleus coop custom resolution, nucleus coop stretched

Still Having Issues?

If none of the above solutions resolve your issue, the best places to get help are:

  • r/nucleuscoop on Reddit — Search for your specific game and error message. Most issues have been encountered and solved by someone in the community.
  • GitHub Issues — Report reproducible bugs that are not handler-specific.
  • Game setup library — Check the handler page for your game; handler-specific issues are often documented there.