Xml.Loaddata - Data at the Root Level Is Invalid. Line 1, Position 1

xml.LoadData - Data at the root level is invalid. Line 1, position 1

The hidden character is probably BOM.
The explanation to the problem and the solution can be found here, credits to James Schubert, based on an answer by James Brankin found here.

Though the previous answer does remove the hidden character, it also removes the whole first line. The more precise version would be:

string _byteOrderMarkUtf8 = Encoding.UTF8.GetString(Encoding.UTF8.GetPreamble());
if (xml.StartsWith(_byteOrderMarkUtf8))
{
    xml = xml.Remove(0, _byteOrderMarkUtf8.Length);
}

I encountered this problem when fetching an XSLT file from Azure blob and loading it into an XslCompiledTransform object.
On my machine the file looked just fine, but after uploading it as a blob and fetching it back, the BOM character was added.

Data at the root level is invalid. Line 1, position 1 -why do I get this error while loading an xml file?

The LoadXml method is for loading an XML string directly. You want to use the Load method instead.

Data at the root level is invalid

This:

doc.LoadXml(HttpContext.Current.Server.MapPath("officeList.xml"));

should be:

doc.Load(HttpContext.Current.Server.MapPath("officeList.xml"));

LoadXml() is for loading an XML string, not a file name.

XDocument.Load(url) Error: Data at the root level is invalid. Line 1 position 1

All I had to do was to set the headers to accept xml like so:

        try
        {
            string url = "http://myfirsturl.com";
            var request = (HttpWebRequest)WebRequest.Create(url);
            request.Accept = "application/xml"; // <== THIS FIXED IT

            using (HttpWebResponse response = (HttpWebResponse)request.GetResponse())
            {
                using (Stream stream = response.GetResponseStream())
                {
                    XDocument doc = XDocument.Load(stream);
                    Console.WriteLine(doc);
                }
            }
        }
        catch (Exception ex)
        {
            Console.WriteLine(ex);
        }

Thanks for the comments and help!

LoadXml - Data at the root level is invalid. Line 1, position 1

As you know that there is only one <ID>, <birthday>, etc. in each <student> node you can use SelectSingleNode.

Although it looks like .Value would get you what appears to be the value, it is more fiddly than that: XmlNode Value vs InnerText.

I assume you put in the xmlns="namespace" from seeing similar things in other XML. In this case, unless you are actually using it, it will only complicate matters.

To validate a date, use DateTime.TryParseExact and give it a format string - there is no need for a complicated regex which would need to be different if you changed to a better date format like yyyy-MM-dd.

You might as well declare the regexes outside the loop to keep the code inside the loop a bit tidier.

It is always frustrating to get a message that says something like "Date error" when it doesn't tell you where or what the erroneous data is.

So, with this XML file located in my "C:\Temp" directory (I don't know why you would use "us-ascii" rather than "utf-8"):

<?xml version="1.0" encoding="us-ascii" standalone="yes"?>
<studentTable>
    <student>
        <ID>0q</ID>
        <student_name>John*</student_name>
        <birthday>25/109/1997</birthday>
    </student>
</studentTable>

and this console application:

Imports System.Text.RegularExpressions
Imports System.Xml

Module Module1

    Sub Main()
        Dim lstErrs As New List(Of String)

        Dim idRegex = New Regex("^[0-9]*$")
        Dim nameRegex = New Regex("^[a-zA-Z]+(([',. -][a-zA-Z ])?[a-zA-Z]*)*$")
        Dim dateFormat = "d/M/yyyy"

        Dim xdoc As New XmlDocument()
        xdoc.Load("C:\Temp\students.xml")

        Dim nodelist = xdoc.SelectNodes("//studentTable/student")

        For Each node As XmlNode In nodelist

            Dim id = node.SelectSingleNode("//ID").InnerText
            Dim dob = node.SelectSingleNode("//birthday").InnerText
            Dim name = node.SelectSingleNode("//student_name").InnerText

            If Not idRegex.IsMatch(id) Then
                lstErrs.Add("Invalid ID number " & id)
            End If

            If Not DateTime.TryParseExact(dob, dateFormat, Nothing, Nothing, New DateTime) Then
                lstErrs.Add("Invalid birthday " & dob)
            End If

            If Not nameRegex.IsMatch(name) Then
                lstErrs.Add("Invalid Name " & name)
            End If

            Console.WriteLine($"{id} {dob} {name}") '' for checking

        Next

        Console.WriteLine(String.Join(vbCrLf, lstErrs)) '' show the errors

        Console.ReadLine()

    End Sub

End Module

I got this output:

0q 25/109/1997 John*
Invalid ID number 0q
Invalid birthday 25/109/1997
Invalid Name John*

---

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