I just wanted to let you know that I didn't have serious problems going from XWiki 0.9.1252 to XWiki 1.0B3 with a Postgres database. Basically, I followed the instructions in: http://www.xwiki.org/xwiki/bin/view/Main/ReleaseNotesXWiki10Beta3 As reported earlier, you'll get an exception ("Could not execute JDBC batch update") connecting to XWiki 1.0B3 for the first time. Analyzing the error message in xwiki.log: Batch entry 0 insert into xwikidoc (XWD_FULLNAME .) SQL ERROR: null value in column "xwd_archive" violates not-null constraint leads to an easy conclusion: remove the not-null constraint from the xwd_archive column in the xwikidoc table. The SQL statement is: ALTER TABLE xwikidoc ALTER COLUMN xwd_archive DROP NOT NULL; After running this SQL statement the connection was done successfully and I could load the XAR file as described in the instructions. In my case, only one thing was different from the old XWiki. All the memberships in XWikiAllGroup were gone. Only the ADMIN user was a member. So I created a Ruby script to add all users to XWikiAllGroup in the database. This can of course also be done manually. I don't know if this works in all Postgres cases. BTW, I did at the same time a database upgrade from PG 8.1.3 to 8.2.1. Rudolf VanderLeeden SysAdmin Logic United GmbH (Germany)