I recently upgraded Magento 2.07 to Magento 2.1 and then to 2.1.1 but now I get the MySQL error ERROR 1054: 1054: Unknown column 'entity_id' in 'NEW' any time I try to import a product or update a product attribute.
I can't re-import my DB backup either because MySQL reports errors whilst importing the backup about NEW.entity_id
Just toggle your indexer mode from schedule to realtime and then back to schedule. You can use the Magento Admin (System->Index Management) or the command line tool thus:
bin/magento indexer:set-mode realtime
bin/magento indexer:set-mode schedule
As described in the Magento2 documentation.
The error is due to some tables eg catalog_product_entity_int having triggers on them so that the scheduled indexer knows what to index. The module CatalogStaging (or one of its dependencies) changes a column name in the table from entity_id to row_id but the trigger does not get updated so it still refers to NEW.entity_id when the entity_id column no longer exists.
The triggers are created when the index mode is set to scheduled so this situation may affect any DB of a Magento install that has been set to index on schedule before upgrading to 2.1.
The fix is simple but not obvious : toggle the indexer to realtime (update on save) and then put it back to schedule. This clears the triggers and then recreates them with the correct reference to the updated column name: NEW.row_id in the trigger as now required by the Magento_CatalogStaging module
Suppletion: I ran into this problem, by forgetting to enable maintenance mode on my local work. After enabling the error was gone, by re-running the same commands for setup upgrade
