I set up selfoss with MySQL and used db_prefix=selfoss_ . The setup of the database was done correctly, in phpMyAdmin I could see selfoss_items and the other tables. But after login I got a blank page with the message "Ein Fehler ist aufgetreten".

In the log I found these messages:

07-10-15 23:44:21 Debug logged in using valid session
07-10-15 23:44:21 Debug Establish database connection
07-10-15 23:44:21 Error PDOStatement: Table 'DATABASE.items' doesn't exist

Without the prefix (db_prefix=) the problem did not occur.