Smarty templates throw syntax error when used with specific themes

I seem to get this php error:

[Mon Jul 23 14:45:43.877604 2018] [php7:error] [pid 1753] [client] PHP Fatal error: Uncaught → Smarty Compiler: Syntax error in template “app:app:frontendcomponentsloginFo” on line 71 “{url|assign:registerUrl page=“user” op=“register” source=$source}” unknown modifier ‘assign’ ← \n thrown in /var/www/html/lib/pkp/lib/vendor/smarty/smarty/libs/sysplugins/smarty_internal_templatecompilerbase.php on line 71

when using these two themes:

I’m using OJS 3.2 in an Ubuntu docker container.

Are you sure that you are using OJS 3.2? The latest production release is 3.1.1-2.

As I remember sysplugins directory appears only from Smarty 3 and the latest Smarty version in a current OJS release is 2.6. Obviously, those themes are not supporting Smarty 3 (yet). From where you get this OJS release?

Yes I’m running 3.2, my DockerFile clones the OJS repository to get the most recent version. Is there a release branch for the OJS github repository that I can use to get the most recent version, or should I stick to the 3.1.1 branch?

Ah, I see that master branch already contains new Smarty library version.

Yep, 3.1.1 is the latest stable release.

Switching to a clone of the most recent stable version seemed to have fixed the issue.