Shipping with all the latest performance improvements and bug fixes from the long-term supported Qt 5.9 branch, Qt 5.9.1 is the first patch release of the series, which means that it doesn’t add any new functionality. There are a bunch of fixes implemented in Qt 5.9.1, and we recommend studying the full changelog, which contains detailed information about every single component that has been updated in this maintenance release. Included in the Qt 5.9.1 offline installer packages, there’s the first point release of the Qt Creator 4.3 IDE (Integrated Development Environment), which fixes a memory leak in code completion affecting 32-bit Windows users.