Just to be sure, is “last WordPress version” the 5.8?
wp_enable_block_templates is a function added in the version 5.8 of WordPress. You should find it in wp-includes/theme-templates.php as you can see here.
Check if that function is actually present in your file. If not, probably something gone wrong during the updating. How did you do that? Manually or from the dashboard?
As SallyCJ suggested, just a new correct updating should solve the problem.