cannot import name 'L2Norm' from 'megatron.core.transformer.torch_norm'

[jakubMitura14]

Describe the bug

When trying to use nemotron ultra in nemo i get """cannot import name 'L2Norm' from 'megatron.core.transformer.torch_norm'"""

Steps/Code to reproduce bug

from nemo.collections import llm
llm.import_ckpt(model=llm.LlamaNemotronModel(llm.Llama31NemotronUltra253BConfig())
                , source='hf://nvidia/Llama-3_1-Nemotron-Ultra-253B-v1-FP8'
                ,output_path='/dataa/temp/nemo_output')

Expected behavior

Environment overview (please complete the following information)

slurm apptainer

instaled libraries on 08.05.2025 via

    python3 -m pip install --no-cache-dir Cython flashinfer-python
    # python3 -m pip install --no-cache-dir nemo_toolkit[all]
    python3 -m pip install --no-cache-dir 'nemo_toolkit[all]@git+https://github.com/NVIDIA/NeMo.git@main'
    echo "Cloning and installing Megatron-LM..."
    git clone https://github.com/NVIDIA/Megatron-LM.git
    cd Megatron-LM
    # Install in development mode
    python3 -m pip install -e .

Additional context
Nvidia A100

[suiyoubi]

"""cannot import name 'L2Norm' from 'megatron.core.transformer.torch_norm'"""

This seems to be a mismatch mcore version issue
Latest mcore has this class defined here: https://github.com/NVIDIA/Megatron-LM/blob/main/megatron/core/transformer/torch_norm.py#L54
but seems like it cannot be located in your env

[jakubMitura14]

It is possible; thanks !

[suiyoubi]

anyways, if you just want to run llama nemotron, you don't really need this, because L2Norm is only used for llama4, you can hack your code a little bit to get rid of this import if your goal is to run llama nemotron