Common XML Errors & How to Fix Them
Learn about the most frequent XML mistakes developers make and how to fix them. Use our XML validator below to check your own code.
XML Error Guides
Click any error for a detailed explanation, code examples, and step-by-step fix instructions.
Unclosed Tag in XML
Fix the XML unclosed tag error fast. Learn why every opening tag needs a matching closing tag or a self-closing form, with clear examples you can copy.
Mismatched Tags in XML
XML tag names are case-sensitive. Learn how to fix mismatched opening and closing tags, spot nesting mistakes, and make your XML well-formed once more.
Unquoted Attribute Values in XML
Every XML attribute value must be wrapped in quotes. Learn how to fix unquoted attribute errors, with clear side-by-side examples and a quick checklist.
Unescaped Special Characters in XML
Characters like &, <, and > must be escaped in XML text content. Learn how to fix unescaped character errors using entities or a CDATA block the right way.
Multiple Root Elements in XML
XML allows exactly one root element. Learn how to fix the multiple root elements error by wrapping your content in a single parent tag, with examples.
Invalid or Missing XML Declaration
Learn how to write a correct XML declaration and fix common mistakes like wrong attribute order, missing encoding, or stray whitespace before the prolog.