'SmartyException' with message 'Unable to load template file-Collection of common programming errors

What’s this? Does any error in the configuration file? Following is the full error.

Fatal error: Uncaught exception ‘SmartyException’ with message ‘Unable to load template file ‘index.tpl” in /var/www/stoke/libs/sysplugins/smarty_internal_templatebase.php:127 Stack trace: #0 /var/www/stoke/libs/sysplugins/smarty_internal_templatebase.php(374): Smarty_Internal_TemplateBase->fetch(‘index.tpl’, NULL, NULL, NULL, true) #1 /var/www/stoke/index.php(41): Smarty_Internal_TemplateBase->display(‘index.tpl’) #2 {main} thrown in /var/www/stoke/libs/sysplugins/smarty_internal_templatebase.php on line 127

I’m using Smarty 3 at Ubuntu Linux in LAMP server.