Encoding request parameters
Many of the REST Services APIs require URL parameters and query string parameters. If these parameter strings contain special characters such as a space, forward slash, plus sign, and so on, they must be URL encoded to prevent the parameter from being misinterpreted. Typically, the programming language that is being used has a method for properly encoding the parameter strings.
Ensure that the encoding occurs only once. HTTP servers can be configured to URL encode by default and this might result in a double encoded value which will cause the REST Services API to fail.