You make a great content type, you drag 'n drop a lot of fields, it was an awesome site powered by seblod ! now client want to make adjustment, you add another field and BANG !... slap in the head... the frontend goes to "Oops! Template not found"

This probably similar to your problem, sometime the field that already assigned gone when you save... DAMN SEBLOD  ! ... No ! Seblod Rocks !... DAMN BROWSER!

Here's one of the reason for the most bugs : SEBLOD UI depend with Javascript ! A lot of bugs can come from SEBLOD UI due to browser issue, because the javascript used synchronous process,  so if you take an action before the javascript loads completely, you're likely will have this bug.

Here's my solution for Missing a Template in Seblod:

1. Database checking

For Content Type/Site/Form, search on table #_cck_core_types , there will be column for template_admin, template_site, template_content, and template_intro , this supposed have value of template id (look template id in #_cck_core_templates)

For Search/List, seach on table #_cck_core_searchs, there will be column for template_search, template_filter, template_list, template_item, this also suppoed to have valid value from template id

2. Reverse Engineering

here's several place that product this error:

libraries/cck/base/form/form_inc.php (line 99)
libraries/cck/base/list/list_inc.php (line 128)
/cck/base/list/list_inc_list.php (line 18 and 60)

Try to modify the error message thrown to individual message, for something like 'Oops! Template not found..1',''Oops! Template not found..2', etc

From there you can traceback easily