Upgrade mediawiki error 1.21

 A database error has occurred. Did you forget to run 
maintenance/update.php after upgrading?  See: 
https://www.mediawiki.org/wiki/Manual:Upgrading#Run_the_update_script

Query: SELECT  
page_id,page_len,page_is_redirect,page_latest,page_content_model  FROM 
`wiki_page`  WHERE page_namespace = '0' AND page_title = 'Main_Page'  
LIMIT 1  

Function: LinkCache::addLinkObj

Error: 1054 Unknown column 'page_content_model' in 'field list' (localhost)

cara memperbaiki : 

1. ALTER TABLE wiki_revision ADD rev_sha1 varbinary(32) NOT NULL default '';

2. php update.php