Error creating the ROS 2 Node: Unable to launch .../libmwros2server.exe

Hello,

I am trying to use the Simulink ROS2 blocks and receive this error.

MATLAB System block 'untitled/Publish/SinkBlock' error occurred when invoking 'setupImpl' method of 'ros.slros2.internal.block.Publisher'. The error was thrown from '
 'C:\Program Files\MATLAB\R2025b\toolbox\ros\mlros2\ros2node.m' at line 552
 'C:\Program Files\MATLAB\R2025b\toolbox\ros\mlros2\ros2node.m' at line 166
 'C:\Program Files\MATLAB\R2025b\toolbox\ros\slros2\+ros\+slros2\+internal\+block\Publisher.m' at line 83
 'C:\Program Files\MATLAB\R2025b\toolbox\simulink\ui\studio\config\m\+SLStudio\StartPauseContinue.p' at line 0
 'C:\Program Files\MATLAB\R2025b\toolbox\simulink\ui\studio\config\m\+SLStudio\ToolBars.p' at line 0'.  
Caused by:
Error creating the ROS 2 node untitled_90580.
Server failed to start. Details: Unable to launch Simple server: Unable to launch C:\Program Files\MATLAB\R2025b\toolbox\ros\bin\win64\libmwros2server.exe
because: An error occurred while initializing child process:  While attempting to execute "C:\Program Files\MATLAB\R2025b\toolbox\ros\bin\win64\libmwros2server.exe -mvmInputPipe 8792 0 0 0 0 0 -mvmOutputPipe 0 10692 0 0 0 0": CreateProcessW: The parameter is incorrect [system:87]
Component:Simulink | Category:Block error

I am using a Windows 11 computer. Unfortunately, it is not an option for me to switch to a Linux duel boot or container based setup, which I understand is prefered for ROS. The models I am using also need Unreal Engine for co-simulation, which I have only been able to get working on Windows.

I am only able to find two other questions with similar issues. One is not relevant here because it is about windows 7, the other says it is an environmental variable issue, but the suggested fix does not work.

https://www.mathworks.com/matlabcentral/answers/1958339-unable-to-start-ros2-node

https://www.mathworks.com/matlabcentral/answers/501668-why-do-i-get-an-error-when-trying-to-create-a-ros2-node-on-windows-7

Thank you for the help! Please let me know any additional information I can provide.

Kory

Answer 1

[Isha]

Hello,

The key part of the error is:

CreateProcessW: The parameter is incorrect [system:87]

This is a Windows error (ERROR_INVALID_PARAMETER) that occurs while MATLAB is attempting to launch libmwros2server.exe, before the ROS 2 node itself is created.

Since you already tried the environment-variable workaround from the related MATLAB Answers post and it did not resolve the issue, it may be useful to further isolate whether the problem is with the ROS 2 server executable itself or with the environment used to launch it.

A few things worth trying:

Check whether the issue occurs outside Simulink:

ros2node("/test")

If the same error occurs, then the issue is likely not specific to the Simulink ROS 2 blocks. Try launching the executable directly from a Command Prompt

"C:\Program Files\MATLAB\R2025b\toolbox\ros\bin\win64\libmwros2server.exe"

This may help identify whether Windows is encountering a missing DLL, permissions issue, or other startup problem before MATLAB can start the process.

If you have other software installed that modifies the runtime environment (for example ROS 2, WSL, Docker, Conda, Unreal Engine integrations, or Visual Studio toolchains), consider checking whether the system PATH or other environment variables have become unusually large. As a diagnostic step, you can check the current PATH length from PowerShell:

$env:PATH.Length

Generate a ROS support file and attach it to the discussion:

ros.internal.generateSupportFile

This can provide additional information about the ROS 2 configuration and environment on the machine.

I also found a recent R2025b/Windows 11 report where ROS 2 node creation failures were traced to stale Fast DDS shared-memory state, although the reported error was different from the CreateProcessW [system:87] error shown here. It may therefore be worth checking for any orphaned ROS/Fast DDS processes or shared-memory artifacts as part of the investigation. Unable to create ROS2 node - MATLAB Answers - MATLAB Central

Hope this helps.