After running strapi (postgres db) migrated to 4.3.x I've a key violation
error: insert into "strapi_core_store_settings" ("environment", "key", "tag", "type", "value") values ($1, $2, $3, $4, $5) returning "id" - duplicate key value violates unique constraint "strapi_core_store_settings_pkey"
to make it short the fix is to update
strapi_core_store_settings_id_seq
with the following sql script
SELECT setval('strapi_core_store_settings_id_seq', COALESCE((select max(id) from strapi_core_store_settings), 0), true)