https://www.icyphoenix.com/viewtopic.php?f=2&t=9609&p=60732#p60732
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Informpro
Tue 16 Aug, 2016 23:24

Re: Integramod And Icy Phoenix Questions
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I think I see what the problem is.

There are two issues:
 - First off, the theme cache isn't cleared. So it keeps looking for phpBB2's subSilver.
 - Secondly, the CMS is incorrectly set up, there are no pages created. You need to manually go to cms.php to create one.


So, we need to fix this. If you REALLY want to do it yourself in the meantime, do this:
[list=1]
[*]Open your board locally (with everything backed up, yada yada yada)
[*]Save config.php somewhere (I named mine __config.php)
[*]Delete everything but that file (keep images/ and uploads/ I guess. At least you have them in your backup. The exact list of files is listed in the file you linked).
[*]Upload IP files in the same directory
[*]Delete IP's config.php
[*]Put back your config.php (rename __config.php to config.php)
[*]Visit install/database_upgrade.php
[*]"Please click Here to update!"
[*]Open config.php, replace "PHPBB_" with "IP_" manually. install/install.php has an action that does it, but... To open install/install.php, you need that done. Sorry :(
[*]Go to login_ip.php, and login with your administrator.
[*]You'll be redirected to a blank page, or see "Template->loadfile(): File ./templates/default/layout/ for handle body is empte"
[*]In your URL, replace "index.php" with "cms.php" (it's important that you keep your SID)
[*]Login again (needed to administrate the website)
[*]Go to "CMS pages"
[*]Click "Add new page"
[*]Select whichever one you like (3 columns, 2 columns). Give it a name (like "index").
[*]Submit.
[/list]


Here! Your site now fully works. You don't get the nice default portal, though, but it's easy enough to set it up yourself :).
Obviously this is sub-optimal – I just wanted to give you "A Way". We'll have to rework this upgrade procedure, but at least you're not "stuck" if really needs be...