I moved 6.5 to a new server running MySQL 5 and PHP 5. I installed 7.3. Everything worked fine up til the import step. The 6.5 importer imports the categories and users but when it gets to the forums, after three it stalls. No messages or errors. It just sits there. I reset some timing values as suggested in another thread about timing out (you can change the max_execution_time for PHP locally on a shared server using a .htaccess file). Nothing worked - it stalls in the same place. I am hoping this is a known issue with the importer on 7.3 that will be fixed soon.