Change Magento 2 theme without using admin panel?

Question

Switched to the default Blank theme this morning for a demo and was immediately locked out of both admin and front-end with a bunch of errors.

Is there a way to toggle the theme through the config files?

Answer 1

Try updating your theme id in core config database table

UPDATE core_config_data SET `value` = NULL WHERE path = 'design/theme/theme_id';

Also try

{magento root}/bin/magento setup:upgrade
{magento root}/bin/magento cache:flush

Answer 2

In order to change magento2 theme without using admin panel do the following 2 steps.

Step1: Database

1. UPDATE core_config_data SET value = NULL WHERE path = 'design/theme/theme_id'
2. Go to your theme table and delete the entry for your created theme.

STEP 2 : Flush cache

php bin/magento cache:flush