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On this site I've learned:

  • There is a new version every 4 months
  • every third version is a long-term-release (LTR) which is supported until release of the next LTR

This means that if you update QGIS once a year to the new LTR, you are always running a fully-supported version, is that correct?

Our administration (federal ministry) follows a very strict security policy. Every software is thoroughly scanned and it takes weeks until they start the rollout. Do you think there are versions which "last longer" so that we can work with them for more than one year?

According to the list in the upper link, the newest LTR is 3.22.12, but in the download section it says "Long term release (most stable): 3.16", whereas 3.22 is shown as "newest" (but not LTR?)

Which version should we go for if we are seeking long support and stability?

offeltoffel
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    The next LTR is 3.22.4, released Feb 2022 -- when 3.16 is discontinued. The version 3.22 will receive monthly stability updates until Jan 2023, to benefit from these, you (or your IT) will still need to install these updates. – Matthias Kuhn Nov 14 '21 at 13:00
  • oh my God, I missed out on the year "2022". That was the mistake... sorry for that and thank you for correcting – offeltoffel Nov 15 '21 at 06:44

1 Answers1

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Short answer

Right now (Nov. 2021), get version 3.22 for long support until Feb. 2023. QGIS 3.16 will not be supported after Feb. 2022.

Numbering of versions

Regular releases are numbered with even version numbers: 3.16, 3.18, 3.20, 3.22. Odd-numbered versions (3.17, 3.19, 3.21, 3.23) refer to development versions that are used for testing purpose, not for productive usage.

Release pattern for QGIS versions

There are always two different main QGIS versions currently supported: LTR (long term release, for stability) and regular realease (newest version with most features). Every four months (three times a year: February, June and October), a new main version is released - additionally, a point release for bug fixes, enhancing the two currently active versions, is released once a month: 3.22.0, 3.22.1, 3.22.2, 3.22.3 etc.

Every 3rd main version (3.4, 3.10, 3.16, 3.22 ...) starts as a regular release, but turns to a LTR after four months when the next regular version is released. So for the first four months of its lifecycle, future LTRs are just "normal" releases and only then they finally become a LTR.

Current situation (Nov. 2022)

Right now (Nov. 2021), QGIS 3.16 is LTR and 3.22 (released Oct 21) is current (newest) version. With release of 3.24 in Feb. 2022, 3.22 will replace 3.16 as LTR. 3.22 will be LTR for 12 months (Feb 2022 to Feb 2023). During this time, the regular versions will be QGIS 3.24 (to be released Feb 2022), QGIS 3.26 (to be released June 2022), and QGIS 3.28 (to be released Oct 2022). In Feb. 2023, QGIS 3.28 turns to be new LTR and 3.22 is depreciated as LTR and will no longer be supported.

Support period

So currently no QGIS version is supported for more then 4 months + one year (= 16 months) and this only in case of LTRs (first four months as regular release, then LTR). However, after this lifecycle, such a version should be stable enough to be used for some time and you could rely on that, even if it is not supported any more.

However, consider the comment by @IanTurton:

just installing the first LTR is not sufficient, you have to install the updates too.

See e.g. the current message in the QGIS News feed in the start window: enter image description here

Option to extend support

An alternative would be hiring one of the QGIS developpers to get longer support for a release. This, however, must be dealt directly with one of the developpers (not affiliated): see commercial support on the QGIS website.

QGIS versions and release pattern since version 2.0 (Sept. 2013). Apart from 2017, when the major jump from QGIS 2.x to QGIS 3.x was prepared, in the last years there were three new versions every year, each with substantial new features and functions: enter image description here

Babel
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    Note, that just installing the first LTR is not sufficient you have to install the updates too. – Ian Turton Nov 14 '21 at 18:17
  • Thank you so much for this long and informative answer. Do you know what is included in the "support"? Given that there are mostly basic features that need to work, the need for support should be relatively low, right? Are there security issues like with Windows or a web browser that did not receive security updates? – offeltoffel Nov 15 '21 at 06:56
  • I guess you're right - the need for support if you need mostly basic features should be low. For security issues, I'm not really sure. For a substantial answer, better ask a separate question about this. See also updated content in my answer (current message in the QGIS News feed). – Babel Nov 15 '21 at 13:27