for $organization in doc("http://www.dbis.informatik.uni-goettingen.de/Mondial/mondial-europe.xml")//organization where every $country in //country[population > 10000000] satisfies $country = id($organization/members/@country) (: the above syntax should be allowed but throws the error message shown below. With this -equivalent- syntax, the query is parsed and evaluated correctly: satisfies $country = $organization/members/id(@country) :) return $organization/name[1] (:saxonXQ -s:mondial-europe.xml xqbug.xq java.lang.NullPointerException at net.sf.saxon.expr.parser.LoopLifter.markDependencies(LoopLifter.java:172) at net.sf.saxon.expr.parser.LoopLifter.gatherInfo(LoopLifter.java:116) at net.sf.saxon.expr.parser.LoopLifter.gatherInfo(LoopLifter.java:126) at net.sf.saxon.expr.parser.LoopLifter.gatherInfo(LoopLifter.java:126) at net.sf.saxon.expr.parser.LoopLifter.gatherInfo(LoopLifter.java:126) at net.sf.saxon.expr.parser.LoopLifter.gatherInfo(LoopLifter.java:126) at net.sf.saxon.expr.parser.LoopLifter.gatherInfo(LoopLifter.java:105) at net.sf.saxon.expr.parser.LoopLifter.process(LoopLifter.java:54) at net.sf.saxon.query.XQueryExpression.(XQueryExpression.java:108) at net.sf.saxon.Configuration.makeXQueryExpression(Configuration.java:3576) at net.sf.saxon.query.XQueryParser.makeXQueryExpression(XQueryParser.java:187) at net.sf.saxon.query.StaticQueryContext.compileQuery(StaticQueryContext.java:562) at net.sf.saxon.query.StaticQueryContext.compileQuery(StaticQueryContext.java:624) at net.sf.saxon.s9api.XQueryCompiler.compile(XQueryCompiler.java:650) at net.sf.saxon.Query.compileQuery(Query.java:864) at net.sf.saxon.Query.doQuery(Query.java:327) at net.sf.saxon.Query.main(Query.java:103) java.lang.NullPointerException at net.sf.saxon.expr.parser.LoopLifter.markDependencies(LoopLifter.java:172) at net.sf.saxon.expr.parser.LoopLifter.gatherInfo(LoopLifter.java:116) at net.sf.saxon.expr.parser.LoopLifter.gatherInfo(LoopLifter.java:126) at net.sf.saxon.expr.parser.LoopLifter.gatherInfo(LoopLifter.java:126) at net.sf.saxon.expr.parser.LoopLifter.gatherInfo(LoopLifter.java:126) at net.sf.saxon.expr.parser.LoopLifter.gatherInfo(LoopLifter.java:126) at net.sf.saxon.expr.parser.LoopLifter.gatherInfo(LoopLifter.java:105) at net.sf.saxon.expr.parser.LoopLifter.process(LoopLifter.java:54) at net.sf.saxon.query.XQueryExpression.(XQueryExpression.java:108) at net.sf.saxon.Configuration.makeXQueryExpression(Configuration.java:3576) at net.sf.saxon.query.XQueryParser.makeXQueryExpression(XQueryParser.java:187) at net.sf.saxon.query.StaticQueryContext.compileQuery(StaticQueryContext.java:562) at net.sf.saxon.query.StaticQueryContext.compileQuery(StaticQueryContext.java:624) at net.sf.saxon.s9api.XQueryCompiler.compile(XQueryCompiler.java:650) at net.sf.saxon.Query.compileQuery(Query.java:864) at net.sf.saxon.Query.doQuery(Query.java:327) at net.sf.saxon.Query.main(Query.java:103) Fatal error during query: java.lang.NullPointerException: (no message) :)