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Open-source contributors say they'll pull out of Qt as LTS release goes commercial-only

'There'll be no more work from external/unpaid contributors' – dev

The Qt Company has followed up on its plan to make long-term support releases commercial-only by closing the source for 5.15 today, earning protests from open-source contributors who say that the 6.0 release, which remains open, is not yet usable.

Qt is a cross-platform application framework available both under open-source and commercial licences. It was around one year ago that the Qt Company stated its plan to make LTS releases commercial-only, along with some other changes designed to encourage open-source users either to contribute to the project or buy a commercial licence.

On 8 December CTO and chief maintainer Lars Knoll noted the arrival of Qt 6.0, "the first release of a major new version."

Qt 6.0 has a new graphics architecture which takes advantage of the native 3D graphics API of each platform on which it runs, as well as the next generation of QML (Qt Modeling Language) for defining a user interface. However, Knoll acknowledged that 6.0 still has limitations.

It "does not yet support many of the add-on modules that can be found in Qt 5.15," he said, and also refered to "clean-up work and refactoring" that is still needed as well as forthcoming work on "the stability of the new releases."

Knoll added: "We plan to have most of the important add-ons ported by the time we release Qt 6.2."

Yesterday senior VP Tuukka Turunen posted: "With Qt 6.0.0 released and the first patch release (Qt 6.0.1) coming soon, it is time to enter the commercial-only LTS phase for Qt 5.15 LTS. All the existing 5.15 branches remain publicly visible, but they are closed for new commits (and cherry-picks)... closing happens tomorrow, 5th January 2021.

"After this the cherry-picks go to another repository that will be available only for the commercial license holders... first commercial-only Qt 5.15.3 LTS patch release is planned to be released in February."

According to last year's QT post, the idea is that non-commercial users shift to 6.0 so that they can still use the latest release for free. Responses to Turunen's post suggested that this is not realistic for many users. "That's some brilliant timing, given that no actual qt 6 release even exists yet (yeah, 6.0 is a joke given that you intend to break binary compat in 6.1)," said one developer.

Another said: "Qt6 has half of the modules required by my project not yet available, so upgrading is not possible. On the other hand, 5.15 LTS is closed for the open source users – this is quite a heavy restriction for me since my project is non-profit and open source. Buying a commercial license is not an option."

Turunen responded that "for the open-source users Qt 5.15 is similar to Qt 5.13 and Qt 5.14 (non-LTS releases)."


The problem is that these releases are in effect no longer maintained. If there is a security issue, or a fix needed to support some change in one of the target operating systems, open-source users will not get that fix other than in the not-ready version 6.0.

Open-source contributor Thiago Macieira, an Intel software architect, said of the decision: "That means I will not be participating in the development of those fixes, commenting on what's appropriate or not, reviewing backports, or bug reports."

"Tend to agree," said Konstantin Ritt, another developer. "If there is a decision to close 5.15 sources, there'll be no more work from external/unpaid contributors."

Turunen responded that: "This is well understandable and expected. The Qt Company is prepared to handle the Qt 5.15 LTS phase work."

But this is not a complete answer to the wider question of Qt viability for open-source users.

A possible solution is a community-driven fork of Qt 5.15 to which bug fixes could be backported. This is under discussion here.

David Edmundson, a maintainer for the Qt-based KDE Linux desktop, noted that: "Whilst that is a valid option, it is not an ideal outcome."

Last year Knoll said: "None of these changes should affect how Qt is being developed. There won't be any changes to Open Governance or the open development model."

However, these new complaints demonstrate that the commercially driven changes do impact the development model.

Many open-source projects struggle to reconcile free availability of code with commercial sustainability, but Qt is seemingly not one of them. Its last interim statement for July-September 2020 reported "very strong profitable growth" with net sales up 30.6 per cent year on year and a 26.5 per cent operating margin. ®

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