i just received this very same error.
however i don't believe a phpbb3 upgrade path was of any fault.
i had 3.0.3 phpbb3 running with phpbb3portal installed with absolutely no issues.
all i wanted was to convert to a portal that is in active development.
i used the \contrib\update_phpbb3portal_122.xml instructions to the letter.
when i ran the install.php i got the above mentioned error.
i found no remedy online, so i just refreshed the same path and noticed that the uninstall option showed up.
the board seems to think the conversion went though, but when i view:
http://www.mzriders.com/portal.php i have a seemingly default-configured portal.
1) can anyone confirm if this is what the successful install should look like? (sans the install folder error, i don't want to remove that until i am confident of success)
2) since i did get the installation process to crap out on that error, can someone tell me what was not dune in the installation batch so that i can complete it manually?
3) any ideas as to why i got the error in the first place?