import any nemo collection (asr, nlp or tts) causes segmentation fault because of transformers==4.0.1
Retrying building pytorch etc from source:
Using transformers==4.0.0:
python
import nemo
import nemo.collections.asr as nemo_asr
ERROR .......
site-packages/transformers/trainer_pt_utils.py", line 40, in <module>
    from torch.optim.lr_scheduler import SAVE_STATE_WARNING
I believe SAVE_STATE_WARNING was removed from pytorch a few days ago. I can see this has been fixed in the source code (master branch) for transformers.
I can now import nemo_asr without segmentation fault and without the SAVE_STATE_WARNING error..
Ubuntu 20.04
cuda 11.1
Latest built from source: torch, torchvision, torchaudio, torchtext, pytorch_lightning, apex, horovod, tf-nightly

To reproduce the error (usinng nemo_asr in the example below):

python
Python 3.7.9 (default, Aug 31 2020, 12:42:55) 
[GCC 7.3.0] :: Anaconda, Inc. on linux
Type "help", "copyright", "credits" or "license" for more information.
>>> import faulthandler
>>> faulthandler.enable()
>>> import nemo
>>> import nemo.collections.asr as nemo_asr
[NeMo W 2020-12-11 19:26:29 experimental:28] Module <class 'nemo.collections.asr.losses.ctc.CTCLoss'> is experimental, not ready for production and is not fully supported. Use at your own risk.
[NeMo W 2020-12-11 19:26:29 experimental:28] Module <class 'nemo.collections.asr.data.audio_to_text.AudioToCharDataset'> is experimental, not ready for production and is not fully supported. Use at your own risk.
[NeMo W 2020-12-11 19:26:29 experimental:28] Module <class 'nemo.collections.asr.data.audio_to_text.AudioToBPEDataset'> is experimental, not ready for production and is not fully supported. Use at your own risk.
[NeMo W 2020-12-11 19:26:29 experimental:28] Module <class 'nemo.collections.asr.data.audio_to_text.AudioLabelDataset'> is experimental, not ready for production and is not fully supported. Use at your own risk.
[NeMo W 2020-12-11 19:26:29 experimental:28] Module <class 'nemo.collections.asr.data.audio_to_text._TarredAudioToTextDataset'> is experimental, not ready for production and is not fully supported. Use at your own risk.
[NeMo W 2020-12-11 19:26:29 experimental:28] Module <class 'nemo.collections.asr.data.audio_to_text.TarredAudioToCharDataset'> is experimental, not ready for production and is not fully supported. Use at your own risk.
[NeMo W 2020-12-11 19:26:29 experimental:28] Module <class 'nemo.collections.asr.data.audio_to_text.TarredAudioToBPEDataset'> is experimental, not ready for production and is not fully supported. Use at your own risk.
2020-12-11 19:26:30.074971: I tensorflow/stream_executor/platform/default/dso_loader.cc:49] Successfully opened dynamic library libcudart.so.11.0
Fatal Python error: Segmentation fault

Current thread 0x00007f19db597740 (most recent call first):
  File "/home/daniel/my37/lib/python3.7/site-packages/torch/jit/_script.py", line 940 in script
  File "/home/daniel/my37/lib/python3.7/site-packages/transformers/models/deberta/modeling_deberta.py", line 461 in <module>
  File "<frozen importlib._bootstrap>", line 219 in _call_with_frames_removed
  File "<frozen importlib._bootstrap_external>", line 728 in exec_module
  File "<frozen importlib._bootstrap>", line 677 in _load_unlocked
  File "<frozen importlib._bootstrap>", line 967 in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 983 in _find_and_load
  File "/home/daniel/my37/lib/python3.7/site-packages/transformers/models/deberta/__init__.py", line 11 in <module>
  File "<frozen importlib._bootstrap>", line 219 in _call_with_frames_removed
  File "<frozen importlib._bootstrap_external>", line 728 in exec_module
  File "<frozen importlib._bootstrap>", line 677 in _load_unlocked
  File "<frozen importlib._bootstrap>", line 967 in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 983 in _find_and_load
  File "<frozen importlib._bootstrap>", line 219 in _call_with_frames_removed
  File "<frozen importlib._bootstrap>", line 953 in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 983 in _find_and_load
  File "/home/daniel/my37/lib/python3.7/site-packages/transformers/models/auto/configuration_auto.py", line 28 in <module>
  File "<frozen importlib._bootstrap>", line 219 in _call_with_frames_removed
  File "<frozen importlib._bootstrap_external>", line 728 in exec_module
  File "<frozen importlib._bootstrap>", line 677 in _load_unlocked
  File "<frozen importlib._bootstrap>", line 967 in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 983 in _find_and_load
  File "/home/daniel/my37/lib/python3.7/site-packages/transformers/models/auto/__init__.py", line 6 in <module>
  File "<frozen importlib._bootstrap>", line 219 in _call_with_frames_removed
  File "<frozen importlib._bootstrap_external>", line 728 in exec_module
  File "<frozen importlib._bootstrap>", line 677 in _load_unlocked
  File "<frozen importlib._bootstrap>", line 967 in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 983 in _find_and_load
  File "<frozen importlib._bootstrap>", line 219 in _call_with_frames_removed
  File "<frozen importlib._bootstrap>", line 953 in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 983 in _find_and_load
  File "/home/daniel/my37/lib/python3.7/site-packages/transformers/modelcard.py", line 31 in <module>
  File "<frozen importlib._bootstrap>", line 219 in _call_with_frames_removed
  File "<frozen importlib._bootstrap_external>", line 728 in exec_module
  File "<frozen importlib._bootstrap>", line 677 in _load_unlocked
  File "<frozen importlib._bootstrap>", line 967 in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 983 in _find_and_load
  File "/home/daniel/my37/lib/python3.7/site-packages/transformers/__init__.py", line 85 in <module>
  File "<frozen importlib._bootstrap>", line 219 in _call_with_frames_removed
  File "<frozen importlib._bootstrap_external>", line 728 in exec_module
  File "<frozen importlib._bootstrap>", line 677 in _load_unlocked
  File "<frozen importlib._bootstrap>", line 967 in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 983 in _find_and_load
  File "/home/daniel/my37/lib/python3.7/site-packages/nemo/collections/common/tokenizers/huggingface/auto_tokenizer.py", line 18 in <module>
  File "<frozen importlib._bootstrap>", line 219 in _call_with_frames_removed
  File "<frozen importlib._bootstrap_external>", line 728 in exec_module
  File "<frozen importlib._bootstrap>", line 677 in _load_unlocked
  File "<frozen importlib._bootstrap>", line 967 in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 983 in _find_and_load
  File "/home/daniel/my37/lib/python3.7/site-packages/nemo/collections/common/tokenizers/huggingface/__init__.py", line 15 in <module>
  File "<frozen importlib._bootstrap>", line 219 in _call_with_frames_removed
  File "<frozen importlib._bootstrap_external>", line 728 in exec_module
  File "<frozen importlib._bootstrap>", line 677 in _load_unlocked
  File "<frozen importlib._bootstrap>", line 967 in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 983 in _find_and_load
  File "<frozen importlib._bootstrap>", line 219 in _call_with_frames_removed
  File "<frozen importlib._bootstrap>", line 953 in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 983 in _find_and_load
  File "/home/daniel/my37/lib/python3.7/site-packages/nemo/collections/common/tokenizers/__init__.py", line 16 in <module>
  File "<frozen importlib._bootstrap>", line 219 in _call_with_frames_removed
  File "<frozen importlib._bootstrap_external>", line 728 in exec_module
  File "<frozen importlib._bootstrap>", line 677 in _load_unlocked
  File "<frozen importlib._bootstrap>", line 967 in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 983 in _find_and_load
  File "<frozen importlib._bootstrap>", line 219 in _call_with_frames_removed
  File "<frozen importlib._bootstrap>", line 1035 in _handle_fromlist
  File "/home/daniel/my37/lib/python3.7/site-packages/nemo/collections/common/__init__.py", line 16 in <module>
  File "<frozen importlib._bootstrap>", line 219 in _call_with_frames_removed
  File "<frozen importlib._bootstrap_external>", line 728 in exec_module
  File "<frozen importlib._bootstrap>", line 677 in _load_unlocked
  File "<frozen importlib._bootstrap>", line 967 in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 983 in _find_and_load
  File "<frozen importlib._bootstrap>", line 219 in _call_with_frames_removed
  File "<frozen importlib._bootstrap>", line 953 in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 983 in _find_and_load
  File "/home/daniel/my37/lib/python3.7/site-packages/nemo/collections/asr/models/classification_models.py", line 31 in <module>
  File "<frozen importlib._bootstrap>", line 219 in _call_with_frames_removed
  File "<frozen importlib._bootstrap_external>", line 728 in exec_module
  File "<frozen importlib._bootstrap>", line 677 in _load_unlocked
  File "<frozen importlib._bootstrap>", line 967 in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 983 in _find_and_load
  File "/home/daniel/my37/lib/python3.7/site-packages/nemo/collections/asr/models/__init__.py", line 16 in <module>
  File "<frozen importlib._bootstrap>", line 219 in _call_with_frames_removed
  File "<frozen importlib._bootstrap_external>", line 728 in exec_module
  File "<frozen importlib._bootstrap>", line 677 in _load_unlocked
  File "<frozen importlib._bootstrap>", line 967 in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 983 in _find_and_load
  File "<frozen importlib._bootstrap>", line 219 in _call_with_frames_removed
  File "<frozen importlib._bootstrap>", line 1035 in _handle_fromlist
  File "/home/daniel/my37/lib/python3.7/site-packages/nemo/collections/asr/__init__.py", line 15 in <module>
  File "<frozen importlib._bootstrap>", line 219 in _call_with_frames_removed
  File "<frozen importlib._bootstrap_external>", line 728 in exec_module
  File "<frozen importlib._bootstrap>", line 677 in _load_unlocked
  File "<frozen importlib._bootstrap>", line 967 in _find_and_load_unlocked
  File "<frozen importlib._bootstrap>", line 983 in _find_and_load
  File "<stdin>", line 1 in <module>
Segmentation fault (core dumped)

pip show transformers
shows version 4.0.1 is installed
 
To fix the issue:
pip install transformers==3.5.1