Security Fix: Using an XPath expression employing a scalar expression as a FilterExpr with ExtractValue() or UpdateXML() caused the server to crash. Such expressions now cause an error instead. (Bug#42495)

Incompatible Change: The fix for Bug#33699 introduced a change to the UPDATE statement such that assigning NULL to a NOT NULL column caused an error even when strict SQL mode was not enabled. The original behavior before was that such assignments caused an error only in strict SQL mode, and otherwise set the column to the implicit default value for the column data type and generated a warning. (For information about implicit default values, see Data Type Default Values.)

The change caused compatibility problems for applications that relied on the original behavior. It also caused replication problems between servers that had the original behavior and those that did not, for applications that assigned NULL to NOT NULL columns in UPDATE statements without strict SQL mode enabled. This change has been reverted so that UPDATE again had the original behavior. Problems can still occur if you replicate between servers that have the modified UPDATE behavior and those that do not. (Bug#39265)