matlab 2020b rosgenmsg can't find CMake?

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I used rosgenmsg for ROS1 with Matlab 2020a on Ubuntu 18.04 and it worked fine. Now I'm trying the same command on Matlab 2020b on Ubuntu 20.04. It seems there's a whole new build system using Python and a C++ compiler in the backend instead of Java. I now get an error about CMake not found:
Validating message files in folder '/home/anton/catkin_ws/src/crtk'..Done.
[0/1] Generating MATLAB interfaces for custom message packages... 0%Error using ros.internal.utilities.getCMakeBinaryPath (line 24)
Could not find CMake in your system. Please install CMake version 3.15.5 or higher and rerun the command.
Error in ros.internal.CatkinBuilder.getCMakePath (line 82)
[aPath, aVersion] =
Meawhile, CMake is installed (using apt):
~$ cmake --version
cmake version 3.16.3
CMake suite maintained and supported by Kitware (
~$ which cmake
Any advice on how to proceed to fix this issue? Also, I'm interested in ROS 1 messages (Noetic), not ROS 2.

Accepted Answer

Cam Salzberger
Cam Salzberger on 26 Oct 2020
Hello Anton,
R2020b involved a large replacement of the ROS functionality in MATLAB. As you have found, it supports rosgenmsg natively in the toolbox (no support package required), but does have new dependencies on Python and CMake.
In order to ensure that CMake is available in MATLAB, ensure that it is on the system PATH environment variable. Based on your terminal commands, it seems like it should be. Just to make sure, can you run these from within MATLAB:
!which cmake
!cmake --version
It's possible that the PATH in your terminal and the PATH in the MATLAB environment is different for some reason.
For other requirements (Python, compiler), see the ROS Toolbox System Requirements page.
Albert Thelemann
Albert Thelemann on 27 Oct 2021
I, too, ran into the same problems desribed here with the difference of me having it installed on Windows. I tried most of the stuff mentioned here, but nothing worked so far. I added cmake to path while installing it. I added it to the matlab path via the GUI provided. I work with the Matlab Version 2021b.
The following commands (in Matlab) give the following results back:
  • "which cmake" gives me: "'CMake' not found."
  • !which command doesnt exist
  • "!cmake --version" gives me:
"cmake version 3.22.0-rc1
CMake suite maintained and supported by Kitware ("
I test if it's working by running ("Monitor & Tune" - Button) in the Simulink basic example called "robotROSConnectToRobotExample". After a while it says:
"Could not find CMake in your system. Please install CMake version 3.15.5 or higher and rerun the command.
Caused by: Validation error(s): Could not find CMake in your system. Please install CMake version 3.15.5 or higher and rerun the command."
Could anyone help me with this?

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More Answers (2)

Jakobus Louw
Jakobus Louw on 12 Jun 2021
Edited: Stefanie Schwarz on 27 Sep 2021
I had to use a different solution since the above solution did not solve the problem for me. I am using Matlab R2021a and Ubuntu 18.
!cmake --version
in MATLAB command window produced the follwing error:
cmake: /usr/local/MATLAB/R2021a/bin/glnxa64/ version `CURL_OPENSSL_4' not found (required by cmake)
This is what worked for me:
It seems that the installed cmake version for Ubuntu 18 is v3.10, but Matlab needs version v3.15+ for ROS Toolbox.
Therefore I downloaded version 3.20 from and installed it using this answer (NB: without removing the previous cmake).
Remember to add the export lines to your .bashrc
I could then succesfully run:
folderpath = fullfile('~/catkin_ws/src/mavros')
to build mavros_msg
  1 Comment
Vincenzo Petrone
Vincenzo Petrone on 22 Jul 2021
I'm sorry, this didn't work for me. I followed the same procedure you mentioned, but when I run
!which cmake
I still get
Then, if I run
!cmake --version
I obtain the same output as before:
cmake: /usr/local/MATLAB/R2021a/bin/glnxa64/ version `CURL_OPENSSL_4' not found (required by cmake)
Instead, when I run the same commands on the Linux terminal, I get the right path:
and the right version I installed:
cmake version 3.21.0
I also added the "export" lines in ".bashrc".
Anyone got the same error and solved?

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Neel Bhatt
Neel Bhatt on 24 Jul 2021
Edited: Neel Bhatt on 24 Jul 2021
Jakobus Louw's answer worked for me.
  • There should be a correction to the cmake version: all the 1.xx versions listed in the answer mean 3.xx - i.e. Matlab 2021a needs cmake version 3.15+ (not 1.15+), but overall the steps outlined in this answer are correct.
To summarize: you can follow the following steps:
  1. Download cmake 3.20.5 from
  2. Open a terminal and run the following
  3. cd ~/Downloads/cmake-3.20.5/ # or wherever you downloaded cmake
  4. ./bootstrap --prefix=$HOME/cmake-install
  5. make
  6. make install
  7. export PATH=$HOME/cmake-install/bin:$PATH
  8. export CMAKE_PREFIX_PATH=$HOME/cmake-install:$CMAKE_PREFIX_PATH
  9. matlab
  10. !cmake --version # Check cmake version: it should be 3.20.5
You can now generate custom messages. You may need to generate custom messages using:
% Follow the next steps that appear in the command window
% For instance, if you are using ROS1:
% Note you may not have permissions to run the following two commands
% which will lead to a warning. In this case, close MATLAB and in the
% same terminal (where you ran exports), run MATLAB with sudo access: sudo matlab
clear classes
rehash toolboxcache
rosmsg list % Confirm you have your custom message show up
  1 Comment
Stefanie Schwarz
Stefanie Schwarz on 27 Sep 2021
Thank you, I fixed this in Jacobus' answer to avoid confusion.

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