Square is permanently retiring the legacy Transaction API which has been integrated in Sytist for years. As far as I can tell, this takes effect July 20, 2026. And once it takes effect, the Square integration in Sytist version 5.8.6 and lower will stop working.
This is information I have received via email and I know other Square & Sytist users have received a similar email.
The Sytist version 5.8.7 update has updated Square integration to Payments API.
If you are using the Square payment option, you will need to update your Sytist to version 5.8.7 or higher in order to keep your Square payment option working.
Additional Important Information
The new integration requires PHP 8.2 or higher! (the programming language on the server).
You can see at the bottom of any Sytist admin page what PHP version is being used. If you are not using PHP version 8.2 or higher, you will need to update the PHP version. You can do this either through your hosting control panel (not your Sytist admin) or contact your hosting company to update the PHP version. (This is not a concern with Sytist Hosted).
You must have a location ID in your Square settings in Sytist. Most likely you already do, but check your settings in Sytist (Settings -> Checkout & Payment) to ensure you do. If you don't, follow the instructions to get it.
If you have any questions about this, visit this topic on this in the support forum.