thx for answer, i have memory_limit already at 256 MB, my DB is currently 944 KB in size (i deleted the archive to get free space and want to build the archives with fresh copy).
The error message “Zend_Session is currently marked as read-only” maybe then says there is already a session (but not in tmp\sessions - thats empty) but I don’t know.
It sounds like the problem is a lack of free space in /tmp which is used by (default) by PHP and MySQL for temporary files.
For PHP, look at the session.save_path in /etc/php/php.ini (or similar).
For MySQL, look at the tmpdir setting in /etc/mysql/my.cnf.
For Piwik to use the local tmp/sessions folder that you created, you have to tell Piwik to ignore the master php.ini setting. You can create an .htaccess file to set the session.save_path, or use a bootstrap.php file in your piwik folder, e.g.,