Django ~= 2.0.6

Could not find a version that satisfies the requirement Django~=2.0.6 (from -r requirements.txt (line 1)) (from versions: )
No matching distribution found for Django~=2.0.6 (from -r requirements.txt (line 1))

python3 -m pip install --pre --upgrade Django==2.0.6

Could not find a version that satisfies the requirement Django==2.0.6 (from versions: )
No matching distribution found for Django==2.0.6