So here I am ready to convert my phpbb2 board to the nice new phpbb3. Well I try to run the conversion and I am using 1&1 hosting and it just times out. Do not have a big board either like 44,000 posts. I try again and the same thing. So I start doing some research and find this
http://www.phpbb.com/kb/article/offline-conversions/
Ok that sounds like it may be my only option but it sounds like a lot of work. I continue to search and luckily I then found the following.
http://www.phpbb.com/community/viewtopic.php?f=65&t=985935
I changed the values as stated in the install_convert.php and it seemed to work. It took a pretty long time as what happens is it does a few then gives you something like
Filling tables
Filling table phpbb3_posts:
skip_rows = 31341:
Each time you do it the number will go up and once you get to the number of posts you had in your forum you are all good.
After you go to phpbb3 though remember to resync everything in the control panel, I thought I was done for after all my posts said they were from 1969 but a resync and I was good to go.
Also remember if you make any changes to the design you have to purge the cache in the admin panel first to see them. Also as of right now there are not a ton of mods that are fully developed so you might want to look before you convert.
Good luck!