[Fix] ImportError: libtorch_cpu.so: undefined symbol: iJIT_NotifyEvent

前言

笔者今天（2025 Nov 21 10:34）安装环境：

conda install pytorch==2.3.0 torchvision==0.18.0 torchaudio==2.3.0 pytorch-cuda=12.1 -c pytorch -c nvidia

然后尝试运行时遇到了下面的奇怪报错：

Traceback (most recent call last):
  File "xxx", line 1, in <module>
    import torch
  File "xxx/envs/myenv/lib/python3.12/site-packages/torch/__init__.py", line 237, in <module>
    from torch._C import *  # noqa: F403
    ^^^^^^^^^^^^^^^^^^^^^^
ImportError: xxx/envs/myenv/lib/python3.12/site-packages/torch/lib/libtorch_cpu.so: undefined symbol: iJIT_NotifyEvent

然后检索发现解决方案在https://github.com/pytorch/pytorch/issues/123097，原文如下：

Importing torch raises undefined symbol: iJIT_NotifyEvent from torch/lib/libtorch_cpu.so: when pytorch and MKL 2024.1+ are installed together. Downgrading MKL to 2024.0.0 resolves it.

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目录

目录

• 前言
• 目录
• 解决步骤

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解决步骤

显然就是降MKL的版本，我们先看下有哪些版本：

conda search mkl

笔者得到结果如下：

Loading channels: done
# Name                       Version           Build  Channel             
mkl                         2017.0.4      h4c4d0af_0  pkgs/main           
mkl                         2018.0.0      hb491cac_4  pkgs/main           
mkl                         2018.0.1      h19d6760_4  pkgs/main           
mkl                         2018.0.2               1  pkgs/main           
mkl                         2018.0.3               1  pkgs/main           
mkl                           2019.0             117  pkgs/main           
mkl                           2019.0             118  pkgs/main           
mkl                           2019.1             144  pkgs/main           
mkl                           2019.3             199  pkgs/main           
mkl                           2019.4             243  pkgs/main           
mkl                           2020.0             166  pkgs/main           
mkl                           2020.1             217  pkgs/main           
mkl                           2020.2             256  pkgs/main           
mkl                         2021.2.0    h06a4308_296  pkgs/main           
mkl                         2021.3.0    h06a4308_520  pkgs/main           
mkl                         2021.4.0    h06a4308_640  pkgs/main           
mkl                         2022.0.1    h06a4308_117  pkgs/main           
mkl                         2022.1.0    hc2b9512_223  pkgs/main           
mkl                         2022.1.0    hc2b9512_224  pkgs/main           
mkl                         2023.0.0  h6d00ec8_25399  pkgs/main           
mkl                         2023.1.0  h213fc3f_46343  pkgs/main           
mkl                         2023.1.0  h213fc3f_46344  pkgs/main           
mkl                         2023.1.0  h6d00ec8_46342  pkgs/main           
mkl                         2025.0.0    hacee8c2_941  pkgs/main           

好，降低版本到2024.0.0可以解决，但是个人没有，那就只能降到更早的版本2023.1.0了

conda install mkl=2023.1.0

然后解决此bug。