Abstract : Updating XQuery programs in accordance with a change of the input XML schema is known to be a time-consuming and error-prone task. We propose an automatic method aimed at helping developers realign the XQuery program with the new schema. First, we introduce a taxonomy of possible problems induced by a schema change. This allows to differentiate problems according to their severity levels, e.g. errors that require code revision, and semantic changes that should be brought to the developer's attention. Second, we provide the necessary algorithms to detect such problems using a solver that checks satisfiability of XPath expressions.