[Upgrading] SQLite2 on MyBB 1.4.11 to SQLite3 on MyBB 1.6 upgrade problem

[Tim7]

Hello,

While upgrading MyBB I faced some problems:

1. I had to delete manually '*upgrade_data' table. Upgrade.php script was not able to do it.

2. Now I have this error
"Fatal error: [SQL] []
SQLSTATE[23000]: Integrity constraint violation: 19 column title is not unique in /home/www/forum/inc/db_sqlite.php on line 430"

Looking at database tables, only four of them have at least 19 columns:
forums
users
usergroups
threads
Is it really problem with column title (name?) or something else?

Thank you for any suggestions.