Malformed declaration expecting version

What it means

If a document has an XML declaration at all, that declaration must begin with version. Encoding and standalone are optional and must follow it; a declaration that leads with encoding is not a declaration the parser will accept.

The declaration itself is optional — a document with no <?xml line is perfectly legal and assumed to be version 1.0 in UTF-8. The failure is starting one and then leaving out its only mandatory part.

What usually causes it

• Writing <?xml encoding="UTF-8"?> in the belief that the declaration is only about encoding.
• Assembling the declaration from parts where version is added conditionally.
• Copying a processing instruction and editing it into a declaration.
• Stripping attributes from the first line with a regex that was too greedy.

How to fix it

• Put version first: <?xml version="1.0" encoding="UTF-8"?>.
• Or delete the declaration entirely — UTF-8 and 1.0 are the defaults, so a document without one is fine.
• Never hand-build the first line; every serializer emits a correct declaration.

The same error elsewhere

Different parsers, same defect. If you arrived with one of these messages, you are in the right place.

• Xerces (Java)

  The "version" pseudo attribute is required and must appear first in the XML declaration.

• expat (Python)

  XML declaration not well-formed: line 1, column 6

• .NET System.Xml

  Version number must start with '1.'