.. include:: /Includes.rst.txt ================== TYPO3 Exception 40 ================== .. include:: /If-you-encounter-this-exception.rst.txt Indicates an SQL error has occurred, please check your :file:`ext_tables.sql` files. For example:: The column 'columnname' on table 'tablename' already exists This happens for example if the file :file:`ext_tables.sql` of a TYPO3 extension has the same field twice for a table. :: CREATE TABLE sys_products_fe_users_mm_visited_products ( uid int(11) NOT NULL auto_increment, pid int(11) DEFAULT '0' NOT NULL, tstamp int(11) DEFAULT '0' NOT NULL, crdate int(11) DEFAULT '0' NOT NULL, deleted tinyint(4) DEFAULT '0' NOT NULL, hidden tinyint(4) DEFAULT '0' NOT NULL, tstamp int(11) unsigned DEFAULT '0' NOT NULL, uid_local int(11) DEFAULT '0' NOT NULL, uid_foreign int(11) DEFAULT '0' NOT NULL, qty int(11) unsigned DEFAULT '0' NOT NULL, :: PRIMARY KEY (uid), KEY uid_local (uid_local), KEY uid_foreign (uid_foreign), ); There are 2 fields :sql:`tstamp` in the table :sql:`sys_products_fe_users_mm_visited_products` Removing the second line with the field :sql:`tstamp` from table :sql:`sys_products_fe_users_mm_visited_products` fixes the problem in this case.