The java.net.URISyntaxException: Illegal character in opaque part error occurs when a URL string contains characters that are not valid in certain parts of the URL. This often happens when special characters (like spaces, @, #, etc.) are not properly encoded.
Solution:
Ensure the URL is correctly formatted and encoded.
Use URLEncoder.encode() to encode special characters in query parameters or path segments.
Check for spaces or illegal characters and replace them with %20 or other appropriate encodings.