I'll need FTP access to debug this. I'm not sure what the mysqli converter did to the code, but it is very likely that wouldn't work properly. Our extensions should be used to migrate to MySQLi. Without FTP access I won't be able to help. If you can attach the files referenced in the errors then I might be able to give some input by looking at the referenced line numbers and seeing if I can spot an issue, but really the only effective way to debug is to work with the live files via FTP while reproducing the issues in a browser.