Exception #0 (LogicException): Unable to load theme by specified key: '12'

Question

it's occurred when I tried to change theme from back-end from custom theme to Luma theme.

Unable to load theme by specified key: '12'

I tried:

• check table core_config_data for theme entry and check by changing it.

SELECT * FROMcore_config_dataWHEREpathLIKE '%theme_id%' it show two entry with different scope one if have scope default and other one is store having id 6 so I delete it.

• check table theme for theme id. no luck theme have different id & even i check it by changing id of custom theme after I delete entry and deploy theme.
• match both table(theme and core_config_data ) entry in db.

deleted custom theme completely

• delete all db entry for product & category assign theme.

SELECT * FROM eav_attribute WHERE attribute_code = "custom_theme"

SELECT * from catalog_product_entity_varchar WHERE attribute_id = product custom design attribute id ;

SELECT * from catalog_category_entity_varchar WHERE attribute_id = category custom design attribute id ;

I delete all entry for categories & products assign theme.

it's now saving luma theme in back-end but showing error

to try to solve this issues now it's only luma & blank theme.

I can't find any theme having id 12 entry in db. in following tables theme, core_config_data

Answer 1

Homepage is assigned to my custom theme whose id is 12. I deleted it so I got this by checking cms_page table.

• It's common to have such problem when you working with custom themes and delete theme.
• My Suggestion Please check theme,core_config_data table for theme entry and eav_attribute,catalog_product_entity_varchar,catalog_category_entity_varchar,cms_page,design_change for assign theme to products,categories,cms pages, custom design.