ERROR: After October 2020 you may experience errors when installing or updating packages. This is because pip will change the way that it resolves dependency conflicts.
We recommend you use --use-feature=2020-resolver to test your packages with the new resolver before it becomes the default.
allennlp 0.8.3-unreleased requires spacy<2.1,>=2.0, but you'll have spacy 3.0.5 which is incompatible.
By using "--use-feature=2020-resolver" with pip install (I ran pip install again) spacy version becomes compatible with the allennlp 0.8.3-unreleased version.
The following is the warning