XSD nillable and xsi:nil errors
xsi:nil="true" requires nillable="true" on the element declaration and an empty element body. It does not waive required attributes. Omission requires a permitted occurrence count; an empty string must still satisfy its type.
Distinguish nil, empty and absent
xsi:nil="true" requires nillable="true" on the element declaration and an empty element body. It does not waive required attributes. Omission requires a permitted occurrence count; an empty string must still satisfy its type.
Reproduced engine diagnostics and complete fixes
Original minimal examples checked on 2 November 2026. Engine wording differs; follow the cause, not a message alone.
libxml2-wasm 0.7.2
Element 'r': The element is not 'nillable'.Xerces2-J 2.12.2 / Temurin Java 21.0.13+9-LTS
cvc-elt.3.1: Attribute 'http://www.w3.org/2001/XMLSchema-instance,nil' must not appear on element 'r', because the {nillable} property of 'r' is false.lxml 6.0.2 / libxml2 2.14.6
Element 'r': The element is not 'nillable'..NET 10.0.14 / System.Xml
If the 'nillable' attribute is false in the schema, the 'xsi:nil' attribute must not be present in the instance.Before: fails
<r xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:nil="true"/>Complete XSD (before)
<xs:schema xmlns:xs="http://www.w3.org/2001/XMLSchema"><xs:element name="r" type="xs:string"/></xs:schema>Repeat this check in your workflow
API, Python CLI and GitHub Actions starter are available for automation. The public API is early access; paid CI authentication and SLA are not offered. Pro: US$19/month, 25-file batches and 10 saved schemas. Team: US$49/month, 100-file batches, 100 schemas and five seats.