Wrestling with an error message on a Drupal Commerce site today. I kept getting errors relating to a missing template file with no path and no file name .tpl.php. Fortunatley with a little debugging giving me a pointer to the correct issue queue on Drupal the solution was readily available. So here's a few easy steps to follow in case you have the same issue.
Warning: include(): Failed opening '/var/www/mydevsite.com/htdocs/.tpl.php' for inclusion (include_path='.:/usr/share/php:/usr/share/pear') in theme_render_template() (line 1247 of /var/www/mydevsite.com/htdocs/includes/theme.inc).<br/> Warning: include(/var/www/mydevsite.com/htdocs/.tpl.php): failed to open stream: No such file or directory in theme_render_template() (line 1247 of /var/www/mydevsite.com/htdocs/includes/theme.inc).
Initially thought it was to do with Address Field formatting with a PDF invoice module - but only because that was the last update to the site and the error appeared when I returned to the Order list screen.
Debugging the code showed that that was a red herring and theme.inc highlighted the Order screen to be the culprit.
What appears to be happening is that a theme hook is giving a suggestion pattern for a template but not completing the job - and therefore we are left with no path, no file name and just a template extension - thus htdoc/.tpl.php
With a little further delving and knowing that it was the Order screen that was causing the problem - I found a solution here
Basically it is due to Display Suite not getting a default layout for the order display. This may happen under other cirumstances and therefore worth noting! - Also the fix shouldn't be necessary and there may be a fix from one of the modules in the future.
Steps to fix:
Step one: Create a layout for display suite in the Order setting display (admin/commerce/config/order/display)
Choose One Column as that won't affect your actual layout.
Step Two: Note that the Fields are all now disabled - Set them to display in the Content region
Step Three: That's it - now you will have no more of those errors (for the Order screen....)