Update the schema in doctrine:symfony.

php bin/console doctrine:schema:update --force

Updating database schema...

                                                                               
  [Doctrine\DBAL\Exception\DriverException]                                    
  An exception occurred while executing 'ALTER TABLE book ADD CONSTRAINT FK_C  
  BE5A33112469DE2 FOREIGN KEY (category_id) REFERENCES category (id)':         
                                                                               
  SQLSTATE[HY000]: General error: 1215 Cannot add foreign key constraint       
                                                                               

                                                                          
  [Doctrine\DBAL\Driver\PDOException]                                     
  SQLSTATE[HY000]: General error: 1215 Cannot add foreign key constraint  
                                                                          

                                                                          
  [PDOException]                                                          
  SQLSTATE[HY000]: General error: 1215 Cannot add foreign key constraint  

php bin/console doctrine:schema:update --force