Upgrading the Canvus server from 3.x to 26.x

Guidance on client/server order has changed

An earlier version of this guidance said that a Canvus 26.07 server would reject clients older than 26.07, and that every client had to be updated in the same change window. That claim was withdrawn after review — see Why the earlier advice was withdrawn below.

What changed

Starting with the April 2026 release, Canvus uses calendar versioning.

Version numbers used to encode feature milestones. Now they encode time: YY.MM.PATCH.BUILD. 26.04.0.123 means April 2026, patch 0, build 123. No hidden meaning, no compatibility signal buried in a major version bump — you see the version, you know when it shipped.

The underlying software is the same build process. The only thing that changed is the number on the box.

Client and server compatibility

Any Canvus 26.x client works with any Canvus 26.x server, in either direction. Within the 26 series you can update the client and the server independently, in whichever order suits your estate.

3.x and 26.x do not interoperate. Compatibility is guaranteed only inside a major series; it breaks at every major boundary — between 3.x, the 26 series and a future 27 series.

Client	Server	Result
26.x	26.x	Supported, in either direction
3.x	26.x	Not supported
26.x	3.x	Not supported

Moving from 3.x to 26.x is therefore a migration, not a rolling upgrade. Plan it as a single change with a defined cutover rather than a period of mixed operation. A client that connects to a server too old to speak its protocol is refused outright, with a message telling you to update the server.

Update clients to 26.6.7 or newer

Before 26.6.7, a client that met a canvas item whose type it did not recognize closed the connection rather than skipping the item. From 26.6.7 the client skips what it cannot represent and the canvas still opens without it. A client older than 26.6.7 can therefore disconnect from a newer server that holds newer content. This is the only compatibility break inside the 26 series, and updating the client resolves it.

Why the earlier advice was withdrawn

The earlier text asked customers to update every client in a single change window, which is disruptive and expensive. It named no mechanism, no error message and no version at which the behavior was introduced, and there was no corresponding release note. When the code was traced, nothing was found that refuses a client on the basis of its 26.x version: the connection handshake accepts a broad range of protocol versions, and a client that encounters part of the data model it does not recognize ignores that part rather than disconnecting.

If you were previously advised to delay a server upgrade until every client had been updated, that constraint does not apply.

Upgrade order and fleet coordination

Within the 26 series there is no required order. Update the server and your clients whenever suits you, as long as both stay on supported releases. Keep clients at 26.6.7 or newer: older clients close the connection when they meet canvas content they cannot represent, rather than skipping it.

Moving from 3.x is different. Because 3.x and 26.x do not interoperate, treat it as a migration with a cutover:

Migrate this server and its data first. The data migration is the part that cannot be undone by reinstalling, so take a backup you have restored at least once before you start.
Then update every client to the same major series. A 3.x client cannot connect to this server once it is on 26.x, so schedule the client rollout alongside the cutover rather than after it.

For the client-side steps, see Upgrading the Canvus client from 3.x to 26.x.

Before you upgrade

Verify your maintenance entitlement and license cover the release you are moving to (see License compatibility below). Contact sales if you are unsure.

Upgrade procedure

Verify your maintenance entitlement and license cover the target release (see License compatibility below).
Upgrade the server. For containerised deployments, see the Canvus Server installation guide. For a bare-metal-to-standalone move, see the 3.x to standalone Windows migration runbook — it removes the previous version before installing. If you are moving from bare-metal to containers instead, see Migrating from bare-metal to containers.
Upgrade clients individually, or in batches, as your maintenance schedule allows. Each client picks up 26.4 features as soon as it lands on a 26.4 server.
Verify connectivity from each upgraded client to the server.

License compatibility

License compatibility depends on the license type:

Subscription licenses: continue to work with no change.
Perpetual licenses: some are tied to a specific major version and will need to be re-issued. If the upgraded server refuses to validate an existing perpetual license, contact sales@multitaction.com for an upgraded license key.

See Server licensing for how to activate a license on the server.

What is not changing

Your data. Canvus 26.4.0 reads the same server data as 3.4.x. No migration is required to move the data itself.
Your configuration files. No config changes are needed for the upgrade.