Upgrading to 2.xx with preg_replace error

[kenchix1]

My site is down for now and it just shows this error:

8192: preg_replace(): The /e modifier is deprecated, use preg_replace_callback instead
File: /home/aaaaaaaa/public_html/forum/Sources/Load.php(198) : runtime-created function
Line: 3

Forum is not loading and I am not sure where to start fixing it.  I read on the sticky that I should upgrade the software to 2.xx but I don't know where to start since the forum is not running.

How can I upgrade to 2.xx without damaging the database ?
Should I download the full install ?
Can I use Fantastico to upgrade ?

Thanks.

[Kindred]

First and foremost...  Backup!!

Then... http://wiki.simplemachines.org/smf/Upgrading

[kenchix1]

thank you ! I'll backup and try to upgrade now.