This page is for errors similar to the one below: user error: Duplicate entry '24' for key 1 query: INSERT INTO node (status, moderate, promote, sticky, title, body, format, uid, created, type, teaser, changed, nid) VALUES('1', '0', '1', '0', 'test', 'this is a test', '1', '1', '1149692821', 'story', 'this is a test', '1149692832', '24') in .../includes/database.mysql.inc on line 66. warning: Cannot modify header information - headers already sent by (output started at .../includes/common.inc:384) in .../includes/common.inc on line 192. The likely problem (short form): At some point, the sequence table in your Drupal database was not updated. The solution 1. Access your database. Check the affected table. In this case, the error tells us that it is the node table (query: INSERT INTO node). This also happens with other tables, modify these instructions accordingly. 2. This is the node table, so the problem is the node id (nid). Each node has a unique id. Look at your table, and find the highest node id (nid). If you have many nodes, it may help to sort your table by nid to find the highest one. 3. Go to your sequences table. Change the node id in the sequences table to a number higher than the id you found in step 2.