Saxon

Two xsl:result-document instructions resolved to the same output URI — usually a static href inside a loop. Make the href dynamic.

Not a processor bug: an xsl:message with terminate="yes" fired. The stylesheet stopped itself — read the message text to see why.

Two or more templates match the same node with equal priority. Saxon warns (or errors in strict mode) and picks the last one declared — make the intent explicit.

An XSLT element appears somewhere the language grammar does not allow: wrong nesting, wrong order, or content at the stylesheet top level that must live inside a template.

Two xsl:variable or xsl:param declarations with the same name exist at the same level — often caused by a stylesheet being included twice.

An honest comparison of the free online XSLT testers that actually support XSLT 3.0 — Saxon HE vs Saxon-JS, multiple inputs, validation and trace. Which to pick and why.

How to use xsl:result-document in XSLT 2.0 and 3.0 to produce multiple output files from a single stylesheet. Covers split by category, multi-format output, serialization control, and streaming.

A practical guide to XSLT 3.0 features including streaming, maps, arrays, and JSON support. What to adopt and why.