Troubleshooting

On Ubuntu 24.04

When you got this message in editor's console or Player.log file.

No usable version of libssl was found
Aborted (core dumped)

Install these.

wget -q http://security.ubuntu.com/ubuntu/pool/main/o/openssl1.0/libssl1.0.0_1.0.2n-1ubuntu5.10_amd64.deb
sudo dpkg -i libssl1.0.0_1.0.2n-1ubuntu5.10_amd64.deb 

Library loading issue

If you see a message like the following in Player.log, the simulator failed to load the bundled Assimp native library and aborted during Main.Awake():

[CrashReporter] Dump saved to: .../CrashDumps/crash_20260616_171532_822_001
AssimpException: Error loading unmanaged library from path: ./CLOiSim_Data/Plugins/x86_64/libassimp.so
  at Assimp.Unmanaged.UnmanagedLinuxLibc6LibraryImplementation.NativeLoadLibrary (System.String path) [0x00059] in <...>:0
  at Assimp.Unmanaged.UnmanagedLibraryImplementation.LoadLibrary (System.String path) [0x00008] in <...>:0
  at Assimp.Unmanaged.UnmanagedLibrary.LoadLibrary (System.String libPath) [0x0002d] in <...>:0
  at Main.Awake () [0x00047] in <...>:0

Error loading here means the file was found but could not be loaded (dlopen failed) — it is not a "file not found" error. The usual cause is a missing dynamic library that libassimp.so depends on.

1. Check for missing dependencies with ldd, from inside the build folder:

~/ws/CLOiSim-linux-5.3.8/$ ldd CLOiSim_Data/Plugins/x86_64/libassimp.so
        linux-vdso.so.1 (0x00007365cd478000)
        libz.so.1 => /lib/x86_64-linux-gnu/libz.so.1 (0x00007365cd43c000)
        libminizip.so.1 => not found
        libstdc++.so.6 => /lib/x86_64-linux-gnu/libstdc++.so.6 (0x00007365cac00000)
        libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007365cd353000)
        libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007365cd325000)
        libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007365ca800000)
        /lib64/ld-linux-x86-64.so.2 (0x00007365cd47a000)

Any line ending in => not found is a missing library. In the example above, libminizip.so.1 is missing.

2. Install the missing package. On Ubuntu/Debian, libminizip.so.1 is provided by libminizip1:

sudo apt update
sudo apt install -y libminizip1

Then re-run ldd to confirm there are no remaining not found lines, and start CLOiSim again.

Tip: run.sh runs a preflight check that prints any not found dependency of libassimp.so before launch, so this problem is reported up front in the console.

When you got this message in editor's console or Player.log file.

DllNotFoundException: libdl.so assembly:<unknown assembly> type:<unknown type> member:(null)

Do this.

sudo apt install --reinstall libc6
sudo ln -s /usr/lib/x86_64-linux-gnu/libdl.so.2 /usr/lib/x86_64-linux-gnu/libdl.so

When you got this error message in unity debugging log

debugging log

tail -f ~/.config/unity3d/LGE.CTO.AdvancedRoboticsLab/CLOiSim/Player.log

error message

Failed to load image: The type initializer for 'System.Drawing.GDIPlus' threw an exception.
Fallback handler could not load library /home/nav/cloisim/CLOiSim-linux-4.3.0/CLOiSim_Data/MonoBleedingEdge/x86_64/libgdiplus.so.0
Fallback handler could not load library /home/nav/cloisim/CLOiSim-linux-4.3.0/CLOiSim_Data/MonoBleedingEdge/x86_64/libgdiplus.so.0.so

Please check if below library is installed in advance.

sudo apt install libgdiplus

When CLOiSim freezes (hangs) with no error message

If the simulator becomes unresponsive without crashing or printing an error, attach gdb to the running process and dump the stack trace of all threads for diagnosis:

gdb -p $(pgrep -f CLOiSim) -batch -ex "thread apply all bt" 2>&1 | tee /tmp/cloisim_hang_bt.txt

This saves the backtrace of every thread to /tmp/cloisim_hang_bt.txt. Attach this file when reporting the issue, since it usually shows which thread is stuck and why.

Note: gdb must be installed (sudo apt install gdb), and the command must be run with sufficient permission to attach to the CLOiSim process (use sudo if needed).