Invalid charachters at path

In my Android app, which fetches JSON data from an URL, I have to encode the username and password. If I encode my username and use it in my URL, it throws an Invalid characters at path error. However if I try the URL with the encoded username, it works! I tried to URLEncode the URL and the username part itself, that gives me an internal server error.

Thanks!

not encoded String username: lc118820, Base64 encoded String username: bGMxMTg4MjA=