These are percent-encoding often referred to as URL encoded special characters.
%20 would be a space character while the
%2F is a forward slash
/. I cannot think of why something that fetches content from a URL would have troubles with the encoding as it’s part of the specification.
If you take some time to research, even with those sets of characters, you’ll find a wealth of information on it, including reference tables of what each one is.
If you still require assistance, I would please ask that you take the time to open a new topic to ask your question (in an MVCE way) as this seems off-topic from the original post.
Some helpful references: