Mattermost 10.11 Ends August 15, 2026 — and the Newest Release Is the Wrong Upgrade

Mattermost 10.11 reaches end of life on 15 August 2026. If you run it, security patches stop after tomorrow.

The instinct at that point is to upgrade to the newest release. For Mattermost that instinct is wrong, and the dates show why: the newest release expires on 15 October 2026, while a version released two months earlier runs until 15 May 2027. Getting this backwards means doing the upgrade work twice before Christmas.

In this guide

What actually stops on August 15 The three-month rule, and the two exceptions The LTS label points at the wrong versions Why "upgrade to the latest" costs you time What is still supported on August 16 What to do

What actually stops on August 15

Mattermost 10.11 was released on 15 August 2025 and reaches end of life exactly twelve months later. Its final patch release was 10.11.23 — twenty-three patches over that year, which is a fair signal of how much security maintenance a supported Mattermost line actually receives.

After tomorrow that stops. The installation keeps running; what ends is the flow of fixes into it. Mattermost is self-hosted for most teams, which means an unpatched server sitting on your own infrastructure, usually holding the internal conversations of the entire company.

Scale of the tail

We track 55 Mattermost releases. As of today 51 of them are already past end of life. Mattermost ships fast and retires fast — being a few versions behind is not a mild condition here, it is the default state of most of the release history.

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The three-month rule, and the two exceptions

Mattermost releases monthly, and the support window is short. Measured across all 55 tracked releases:

Support window	Releases	What it means
3 months	42	The standard. Roughly one release of overlap.
4 months	4	Minor schedule slippage.
9–10 months	7	Older, longer-cadence releases.
12 months	2	The only two releases ever given a full year — 10.11 and 11.7.

Two releases out of fifty-five. That is the entire set of Mattermost versions that ever received a year of support, and one of the two dies tomorrow.

This is why 10.11 is the version so many self-hosted teams are on. It was the sensible choice a year ago, for exactly the right reason: it was the one with a long runway. That runway ends on Saturday.

The LTS label points at the wrong versions

Mattermost does mark certain releases as long-term-support, and our lifecycle data carries that flag. Seven releases have it: 10.5, 9.11, 8.1, 7.8, 7.5, 7.1 and 6.3.

Neither 10.11 nor 11.7 is among them — and every one of those seven is already end-of-life, the most recent having expired in November 2025.

Group	Releases	Typical window	Status today
Flagged long-term-support	7	~9 months	All end-of-life
Not flagged, but given 12 months	2	12 months	10.11 ends tomorrow; 11.7 runs to May 2027

So the label and the longest support windows have come apart. One flagged release, 7.5, ran for barely three months. If you pick your target version by looking for the long-term-support marker, you will land on something that expired months ago rather than on 11.7.

Pick by date, not by label. That is the practical lesson, and it is why the rest of this piece talks only about dates.

Why "upgrade to the latest" costs you time

Here is the trap, stated as plainly as the dates allow. Day counts are as of publication, 14 August 2026; the end-of-life dates are fixed.

Version	Released	End of life	Days left at publication	Risk score
11.9 (newest)	2026-07-16	2026-10-15	62	25
11.8	2026-06-16	2026-09-15	32	25
11.7	2026-05-15	2027-05-15	274	10
10.11 (yours, probably)	2025-08-15	2026-08-15	1	25

11.7 is older than 11.9 and outlives it by 212 days. Upgrading to the newest release buys you two months and then puts you back in the same position, having spent the same testing and rollout effort you would have spent going to 11.7.

Anyone following the ordinary rule — take the latest stable — ends up doing this migration twice. Nothing in the version numbers signals which release has the long runway.

What is still supported on August 16

Three versions, and that is the complete list:

Version	Supported until	Latest patch	Verdict
11.7	2027-05-15	11.7.9	The target. Nine months of runway.
11.9	2026-10-15	11.9.1	Newest, but expires in two months.
11.8	2026-09-15	11.8.5	Expires in one month. Not a destination.

Everything else in the Mattermost catalogue — all 51 other tracked releases — is already past end of life as of today.

What to do

If you are on 10.11: plan the move to 11.7, not to 11.9. You are jumping a major version either way, so the testing burden is the same; the difference is whether the result lasts nine months or two.

If you already upgraded to 11.8 or 11.9: you are supported, but only until autumn. Put the next migration in the calendar now rather than meeting it by surprise, and consider whether moving sideways to 11.7 is cheaper than two upgrades.

If you cannot move before Saturday: the realistic controls are the ordinary ones for an unpatched internal service — restrict network exposure, make sure it is not reachable from the public internet, and write the decision down with a date attached. Undocumented end-of-life software is what auditors record as a finding.

One honest note

There is no third-party extended-support market for Mattermost that we are aware of — unlike Linux distributions or long-lived Java frameworks, nobody sells post-EOL patches for it. That makes the upgrade the only real path, and it is why picking the right target version matters more here than it does elsewhere.

Every Mattermost version, its dates and its EOL Risk Score are on the Mattermost lifecycle page, updated at every build from upstream data.