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Recently I tried to upgrade my tiki-wiki installation from 12.2 directly to 13.1 (that's a 3 step upgrade) and got errors in 5 tables. The way I did it was
export my working db;
import it in a new -empty- one;
connect with the 13.1 installation.
In the final stage of db connection I got 5 errors and when I started my 13.1 installation I was unable to edit any page (the edit window opens blank, buttons are invisible, cursor can't be placed anywhere). I really don't know if this problem has to do with these 5 errors (yes, I have asked tiki-wiki forum, still searching there).
Then, I went back, upgraded from 12.2 to 12.3 (one step upgrade) and everything was fine (no errors during db upgrade, editing pages possible).
Are these errors (see below) really important? Could they have anything to do with new installation not working properly? Any advise that could help me resolve the issue?
The errors:
20131218_stored_queries_tiki, create table 'tiki_search_queries etc.
20140109_query_unique_name_tiki (...) Duplicate column name 'description'
20140117_monitor_tiki, create table 'tiki_user_monitors' etc
20140206_add_parser_column_tiki (...) Table'tiki_output' already exists
20140214_goals_tiki, create table 'tiki_goals' etc.

The errors like duplicate column and table already exist are safe to be ignored while upgrading Tiki. You can mark them in the installer using the checkboxes. I don’t think they have anything to do with your blank page issue. Check your server log for fatal errors. Most common reason for blank page is low memory limit. But can be something else too.

Please make sure that the ownership and permissions of the upgraded files match what was there originally. Use:
chown -R name.name *
to change the file ownership where [name] matches what was there before and set file permissions with:
Directories:
find . -type d -exec chmod 755 {} \;
Files:
find . -type f -exec chmod 644 {} \;
some servers use 775 and 664.