importNetworkFromONNX error due to mex

I'm trying to import an ONNX model into Matlab 2025a. However, when I run the command 'importNetworkFromONNX', there is something wrong with the MEX file. Here are the error messages:

错误使用 nnet.internal.cnn.onnx.onnxmex

MEX 文件

'C:\ProgramData\MATLAB\SupportPackages\R2025a\toolbox\nnet\supportpackages\onnx\+nnet\+internal\+cnn\+onnx\onnxmex.mexw64'

无效: 找不到指定的程序。

Answer 1

[Esther]

This seems to be a known issue in MATLAB R2025a Update 1.

Please contact MathWorks Technical Support: Contact Support - MATLAB & Simulink

[凤]

联系了，没有得到有效解决

[Jianghao Wang]

Hello, can you please share what release you are on right now?

If you are on R2025a, the issue should have been fixed.

If you are on R2025b, can you please advise the exact release/update info?

Depending on your release info, here are some potential solutions:

1. use MATLAB Online https://matlab.mathworks.com (this should always work regardless of release)
2. for R2025b Update3 or Update4, please uninstall the ONNX support package and reinstall the most recent 25.2.5 release of the package. For uninstalling, please follow the instructions here: https://www.mathworks.com/help/comm/usrpradio/ug/uninstall-support-packages.html
3. R2025b Update 1 or 2, these should remain unaffected.

Thank you.

[Andrew]

how do I select which version of the package to install? I'm not seeing this option anywhere

[Esther]

Hi @Andrew, can you try with the followings?

First, make sure to upgrade to R2025b Update 4 or later by using Help > Check for Updates:

Then, uninstall the ONNX support package by clicking the "Manage" button in the Add-On Panel and then selcting "Uninstall" in Add-On Manager:

Finally, reinstall the ONNX support package from the Add-On Explorer. To confirm that the most recent version was installed, use:

>> matlabshared.supportpkg.getInstalled

Name Version Base Product

--------------------------------------------------------- ------- ------------

Deep Learning Toolbox Converter for ONNX Model Format 25.2.5