XML parameter not working in embed paginated report URL

Why the raw XML fails

• Characters such as <, >, & and quotes have reserved meanings in a URL. They must be percent-encoded; otherwise the service truncates or rejects the query-string.
• Paginated Report parameters are always received as plain text. If you send an XML fragment you’ll parse it later in the dataset/query.

Recommended approach

1. In the report:
   • Create parameter P_IDS as type Text, allow blank.
   • Inside the dataset (SQL Server example) turn the string back into XML:
     

     DECLARE @xml xml = @P_IDS;
     SELECT x.i.value('.', 'int') AS ID
     FROM   @xml.nodes('/Pr/id') x(i);
             

2. In ASP.NET (Framework) encode the parameter value before concatenating it to the embedUrl:

using System.Web;   // for HttpUtility

var pIdXml   = "<Pr><id>25</id><id>32</id></Pr>";
var start    = startDate.ToString("yyyy-MM-dd");   // format counts!
var end      = endDate.ToString("yyyy-MM-dd");

var query =
    $"rp:P_IDS={HttpUtility.UrlEncode(pIdXml)}" +
    $"&rp:START_DATE={start}" +
    $"&rp:END_DATE={end}";

var embedUrlWithParams = $"{embedInfo.embedUrl}?{query}";

Key points

• Use HttpUtility.UrlEncode (or Uri.EscapeDataString in .NET Core) on every parameter value that might contain reserved characters.
• Ensure the base embedUrl already ends without a query part; add ? once, then & for subsequent parameters.
• If the report only needs multiple numeric IDs you can skip XML entirely and pass them as a multi-value parameter:
  
  

Full Microsoft guidance: Paginated Reports – URL parameters

Try building the URL with the encoding applied and refresh the embedded viewer; you should now see the parameter values arriving intact. If parsing or report execution still fails, copy the final URL into a browser address bar to confirm the encoded XML string is complete.