Upgrading the Canvus client 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. That claim was withdrawn after review — it did not match how the software behaves. See Client and server compatibility below for the current position, and the server page for why the earlier claim was withdrawn.

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.

Upgrade order

Within the 26 series there is no required order. Update clients and the server whenever suits you, as long as both stay on supported releases — and keep clients at 26.6.7 or newer, for the reason above.

Moving from 3.x is different. Because 3.x and 26.x do not interoperate, the server is migrated first and the clients follow:

Migrate the server, including its data. See Upgrading the Canvus server from 3.x to 26.x.
Update the clients to the same major series. Until a client is updated it cannot reach the migrated server.

Plan the cutover so clients are updated close to the server. A 3.x client cannot work against a 26.x server in the meantime.

Before you update

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

Update procedure

Confirm your license covers the target release (see License compatibility).
Download and install the latest Canvus client package for your platform from the downloads page. The installer replaces the previous version.
Verify connectivity from the client to your server.

For the general (non-major-version) client update procedure, see Client updating.

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 updated client refuses to validate an existing perpetual license, contact sales@multitaction.com for an updated license key.

See Client licensing for how to activate a license on the client.

What is not changing

Your canvas data. The 26.x client reads the same server data as 3.4.x — no migration required on the client side.
Your client configuration files. No config changes are needed for the update.