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Upgrading from an older version

Upgrading from v3 to v4

Smarty 4 is mostly identical to Smarty 3. Most notably, it adds support for PHP8 and drops support for PHP7.0 and below. Additionally, some deprecated features that have long been discouraged have been dropped from the language.

Muting PHP8 warnings

If you simultaneously upgrade Smarty to v4 van PHP to v8, you may notice your error logs filling up with warnings about undefined or null template vars due to a change in how PHP handles these. This may be helpful to spot errors, but if you find this annoying, you can use $smarty->muteUndefinedOrNullWarnings() to make Smarty convert these warnings into notices.

ASP tags

You can no longer user ASP-style tags like <% %> and <%= %> in your templates. Replace them with {...} tags.


Check your codebase for SmartyBC. We have dropped deprecated API calls that where only accessible through the SmartyBC class.

No more embedded PHP

We have completely dropped support for {php} and {include_php} tags and embedded PHP in templates. Check your templates for this, and rewrite any embedded PHP blocks, by moving logic to your PHP files or by creating a plugin function.

Other changes

Search your code for the following changes:

  • Smarty::muteExpectedErrors and Smarty::unmuteExpectedErrors API methods have been removed
  • Smarty::getVariable method has been removed. Use Smarty::getTemplateVars instead.
  • Smarty::registerResource no longer accepts an array of callback functions