ERROR: Could not find a version that satisfies the requirement bleach==2.1.2 (from -r requirements.txt (line 1)) (from versions: none)

Question

"pip install -r requirements.txt" is the command which gives the error that couldnot find version that satisfies the requirement bleach."requirements.txt" is a file which has all the python packages to be installed.The question is how to resolve the given command as it indicates the path may be wrong or version mismatch.Kindly help in the same.