Hi. We're using Drools 5.1.0 together with the xdrl format. Now we encounter a problem with the <from> element. We're using it like so: --cut here-- <dro:and-conditional-element> <dro:pattern object-type="EMail" identifier="fctv_17263"/> <dro:pattern object-type="String"> <dro:field-constraint field-name="this"> <dro:literal-restriction evaluator="==" value="true"/> </dro:field-constraint> <dro:from> <dro:expression>fctv_17263.getHeaderValues("X-My-Header"); </dro:expression> </dro:from> </dro:pattern> </dro:and-conditional-element> --cut here-- Now we simply added an additional field-constraint within an and-constraint-connective (for a not null check): --cut here-- <dro:and-conditional-element> <dro:pattern object-type="EMail" identifier="fctv_17263"/> <dro:pattern object-type="String"> <dro:and-constraint-connective> <dro:field-constraint field-name="this"> <dro:literal-restriction evaluator="!=" value="null"/> </dro:field-constraint> <dro:field-constraint field-name="this.toLowerCase"> <dro:literal-restriction evaluator="==" value="true"/> </dro:field-constraint> </dro:and-constraint-connective> <dro:from> <dro:expression>fctv_17263.getHeaderValues("X-My-Header"); </dro:expression> </dro:from> </dro:pattern> </dro:and-conditional-element> --cut here-- But that dies with a: java.lang.RuntimeException: org.drools.compiler.DroolsParserException: org.xml.sax.SAXParseException: <from> is after an invalid element: org.drools.xml.Handler at org.drools.compiler.PackageBuilder.addKnowledgeResource(PackageBuilder.java:545) at org.drools.builder.impl.KnowledgeBuilderImpl.add(KnowledgeBuilderImpl.java:28) ... ... Caused by: org.drools.compiler.DroolsParserException: org.xml.sax.SAXParseException: <from> is after an invalid element: org.drools.xml.Handler at org.drools.compiler.PackageBuilder.addPackageFromXml(PackageBuilder.java:304) at org.drools.compiler.PackageBuilder.addKnowledgeResource(PackageBuilder.java:468) ... 77 more As I'm writing this, I encountered this is related to this: https://jira.jboss.org/browse/JBRULES-2672 I added an updated patch that worksforme to the JIRA. Maybe someone of the Drools team can verify it? BTW: all drools-compiler testcases seem to work (5.1.1) after applying the patch. Thanks Veit