unable to import pytorch-lightning
I installed pytorch-lightning using pip, and I'm running on Mac.
I tried:
! pip install pytorch-lightning --upgrade
! pip install pytorch-lightning-bolts

(finished successfully)
and then:
import pytorch_lightning as pl

and what I get is:
--
-------------------------------------------------------------------------
ImportError                               Traceback (most recent call last)
&lt;ipython-input-3-f3b4217dcea1&gt; in &lt;module&gt;
      7 from torchvision.datasets import MNIST
      8 from torchvision import transforms
----&gt; 9 import pytorch_lightning as pl
     10 from pytorch_lightning.metrics.functional import accuracy
     11 tmpdir = os.getcwd()

/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/pytorch_lightning/__init__.py in &lt;module&gt;
     60     # We are not importing the rest of the lightning during the build process, as it may not be compiled yet
     61 else:
---&gt; 62     from pytorch_lightning import metrics
     63     from pytorch_lightning.callbacks import Callback
     64     from pytorch_lightning.core import LightningDataModule, LightningModule

/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/pytorch_lightning/metrics/__init__.py in &lt;module&gt;
     12 # See the License for the specific language governing permissions and
     13 # limitations under the License.
---&gt; 14 from pytorch_lightning.metrics.classification import (  # noqa: F401
     15     Accuracy,
     16     AUC,

/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/pytorch_lightning/metrics/classification/__init__.py in &lt;module&gt;
     12 # See the License for the specific language governing permissions and
     13 # limitations under the License.
---&gt; 14 from pytorch_lightning.metrics.classification.accuracy import Accuracy  # noqa: F401
     15 from pytorch_lightning.metrics.classification.auc import AUC  # noqa: F401
     16 from pytorch_lightning.metrics.classification.auroc import AUROC  # noqa: F401

/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/pytorch_lightning/metrics/classification/accuracy.py in &lt;module&gt;
     16 import torch
     17 
---&gt; 18 from pytorch_lightning.metrics.functional.accuracy import _accuracy_compute, _accuracy_update
     19 from pytorch_lightning.metrics.metric import Metric
     20 

/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/pytorch_lightning/metrics/functional/__init__.py in &lt;module&gt;
     12 # See the License for the specific language governing permissions and
     13 # limitations under the License.
---&gt; 14 from pytorch_lightning.metrics.functional.accuracy import accuracy  # noqa: F401
     15 from pytorch_lightning.metrics.functional.auc import auc  # noqa: F401
     16 from pytorch_lightning.metrics.functional.auroc import auroc  # noqa: F401

/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/pytorch_lightning/metrics/functional/accuracy.py in &lt;module&gt;
     16 import torch
     17 
---&gt; 18 from pytorch_lightning.metrics.classification.helpers import _input_format_classification, DataType
     19 
     20 

/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/pytorch_lightning/metrics/classification/helpers.py in &lt;module&gt;
     17 import torch
     18 
---&gt; 19 from pytorch_lightning.metrics.utils import select_topk, to_onehot
     20 from pytorch_lightning.utilities import LightningEnum
     21 

/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/pytorch_lightning/metrics/utils.py in &lt;module&gt;
     16 import torch
     17 
---&gt; 18 from pytorch_lightning.utilities import rank_zero_warn
     19 
     20 METRIC_EPS = 1e-6

/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/pytorch_lightning/utilities/__init__.py in &lt;module&gt;
     16 import numpy
     17 
---&gt; 18 from pytorch_lightning.utilities.apply_func import move_data_to_device  # noqa: F401
     19 from pytorch_lightning.utilities.distributed import (  # noqa: F401
     20     AllGatherGrad,

/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/pytorch_lightning/utilities/apply_func.py in &lt;module&gt;
     23 
     24 from pytorch_lightning.utilities.exceptions import MisconfigurationException
---&gt; 25 from pytorch_lightning.utilities.imports import _TORCHTEXT_AVAILABLE
     26 
     27 if _TORCHTEXT_AVAILABLE:

/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/pytorch_lightning/utilities/imports.py in &lt;module&gt;
     54 _TORCH_GREATER_EQUAL_1_7 = _compare_version(&quot;torch&quot;, operator.ge, &quot;1.7.0&quot;)
     55 _TORCH_QUANTIZE_AVAILABLE = bool([eg for eg in torch.backends.quantized.supported_engines if eg != 'none'])
---&gt; 56 _APEX_AVAILABLE = _module_available(&quot;apex.amp&quot;)
     57 _BOLTS_AVAILABLE = _module_available('pl_bolts')
     58 _DEEPSPEED_AVAILABLE = not _IS_WINDOWS and _module_available('deepspeed')

/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/pytorch_lightning/utilities/imports.py in _module_available(module_path)
     32     &quot;&quot;&quot;
     33     try:
---&gt; 34         return find_spec(module_path) is not None
     35     except AttributeError:
     36         # Python 3.6

/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/importlib/util.py in find_spec(name, package)
     92         parent_name = fullname.rpartition('.')[0]
     93         if parent_name:
---&gt; 94             parent = __import__(parent_name, fromlist=['__path__'])
     95             try:
     96                 parent_path = parent.__path__

/Library/Frameworks/Python.framework/Versions/3.8/lib/python3.8/site-packages/apex/__init__.py in &lt;module&gt;
     11                                 ISessionFactory)
     12 from pyramid.security import NO_PERMISSION_REQUIRED
---&gt; 13 from pyramid.session import UnencryptedCookieSessionFactoryConfig
     14 from pyramid.settings import asbool
     15 

ImportError: cannot import name 'UnencryptedCookieSessionFactoryConfig' from 'pyramid.session' (unknown location


I guess this is an outdated issue as we have cut out TorchMetrics to a standalone package. Please, check out the latest PytorchLightning.
