We are pleased to announce that Qt 5.9 will be a Long Term Supported (LTS) release. We have done a lot of improvements to Qt since the previous, Qt 5.6 LTS, and to maximize the benefits for our users we will make Qt 5.9 an LTS release. There will be several Qt 5.9.x patch level releases created during the next three years – also after the next Qt 5.x releases become available. Commercial licensees eligible for technical support will also be able to submit support requests during the whole LTS period.
Since the release of Qt 5.6, our previous LTS release, a huge amount of improvements has been added to Qt. We have done significant work on improving performance, added multiple important new features, and fixed thousands of bugs. Qt 5.9 LTS is a fantastic product that offers substantial improvements over Qt 5.6 LTS. To make it possible for all our users to benefit from these, we will be providing Long Term Support for Qt 5.9.
As with Qt 5.6 LTS, we will be using a phased approach to content in patch level releases for Qt 5.9 LTS. During the first 6 months after release day, an LTS release receives a lot of fixes, including low-priority ones. Then the LTS release enters a 'strict' phase where only critical bugs and security issues are addressed. This will ensure the stability of the LTS releases. During the final year of an LTS release the commit policy is 'very strict', at which phase we only address severe security issues.
For all new projects, we strongly recommend using Qt 5.9 LTS. The upcoming Qt 5.9 LTS will be supported alongside with the earlier Qt 5.6 LTS release, which still allows the use of the old C++98 compilers. As already noted above, Qt 5.9 LTS offers lots of performance improvements as well as a vast amount of other improvements and bug fixes that are not included into Qt 5.6 LTS. Currently, Qt 5.6 LTS is in the 'strict' phase where it only receives selected critical fixes and next it is moving into the ‘very strict’ phase. During this final phase, Qt 5.6 LTS will receive important security fixes only.
According to our LTS promise, we guarantee that Qt 5.9 LTS will be supported for three years via standard support, after which additional extended support can be purchased. During this time, even though following Qt releases (5.10 onwards) are already out, Qt 5.9 LTS will receive patch releases providing bug fixes and security updates. For an LTS release, the amount of patch releases will be higher than non-LTS releases of Qt and we aim to provide these throughout the LTS period. In addition to security fixes, error corrections and improvements provided by the LTS patch releases, we may also add support for new operating system and compiler versions to an LTS release of Qt, when feasible. It should be noted that the deprecated modules and technology preview modules are not subject to the LTS.
Qt 5.9 Beta releases are already available via the online installer, check it out if you have not yet done so. If you do not have the Qt online installer yet, please get it from the Qt Account or the Qt downloads page. We are working hard to further fix and polish it with the target of having the Qt 5.9.0 final out around the end of May 2017.