There's not one single guide to solve all problems. It depends on the problem. It could be some incompatibility with your specific version of MySQL or PHP that we don't know about, it could be that you have done some modifications to your database that weren't expected by the upgrade script, it could be a bug in the upgrade script or it could be a permissions issue, among others. You should always perform a backup before upgrading (even better would be to try the upgrade on a copy of your installation first so that you don't risk altering your original installation, though you have to be sure that you are copying both the installation folder and database and that you are not using your old database in your new installation, so a backup here would also be recommended). If you get an error, restore your backup and try the manual upgrade. If you still get an error, your best bet is to copy the error message and post it in the forum or search the forums for a similar problem or buy support from Feng Office. If you want to get your hands dirty and your error is of the kind of "Error X at line Y" then go to the upgrade file of the current version (public/upgrade/templates/db_migration/<version><codename>.php) and delete all lines upto the one that gave an error and try again. This could work or not, depending on what line caused an error, and it is not recommended if you don't know what you are doing as it may cause upgrade problems in the future.