How to Update an XML File That Is Malformed

Finding the problem in a malformed XML document can be frustrating.

Electronic publishers used Extensible Markup Language (XML) as a text format to meet the challenges of large-scale operations. Currently businesses use XML to exchange data, especially on the Web. XML documents must be well-formed in order to be parsed correctly. If your application indicates your XML document is malformed, you can use a text editor to fix most problems.

Instructions

1. Launch Notepad or another text editor on your PC. Open the XML document in Notepad. You may need to change the "File type" to "All types." Verify your XML document begins with an XML declaration. The declaration should specify the version and encoding that should be used to decode the document; for example, <?xml version="1.0" encoding="ISO-8859-1"?>.

2. Examine the markup of the document. Every start tag should have a corresponding end tag and each of those must be in a specific tree-like structure. The first tag describes the "root element." Its end tag should be at the end of that element. It may have one or more child elements. Each of the child elements must have a start and end tag between the root element's start and end tag. Here's a sample structure:

   <root>

   <child1>character data</child1>

   <child2>

   <subchild1>character data</subchild1>

   <subchild2>character data</subchild2>

   </child2>

   <root>

3. Verify start tags and end tags for each pair use identical case, as tags are case-sensitive. Also, check that all attribute values have single or double quotes. Make any changes necessary and save your file. Make sure the document extension remains .xml.

4. Copy and paste your XML into a validator, such as the one on W3Schools.

Tips & Warnings

• All XML elements must have an end tag and must be properly nested. XML tags are also case-sensitive, and start and end tags must be written in the same case.

• If an element has a value, it must be in quotes.

• If you wish to include comments in your XML document, use the following syntax: <!-- This is a comment. -->

• Avoid the use of the following characters within the data sections of your XML document: &,<, >, ' and ". You must be escaped using numeric character references or string equivalents -- e.g., "&amp;" for "&."

• XML elements cannot begin with a number or punctuation character or begin with the letters "XML" in upper or lowercase. Neither can elements contain spaces.

References

• W3C; Extensible Markup Language (XML); Liam Quin; April 2011

Resources

• W3Schools: XML Validator
• W3School: XML Tutorial