When updating from Admidio 2.x to version 3.x a few special features must be observed. In version 3 the complete structure of the layout has changed. Additionally the update script has been extended.
The location of config.php has changed. This will be deposited not in the main folder, but in the folder adm_my_files. If this folder has the necessary write permissions for Admidio, the config.php is automatically moved to the folder with the update. If the rights do not exist, then you must move the file via FTP to the folder adm_my_files.
Now you can delete the folders adm_program and adm_themes and replace them with the folders of version 3. The index.php in the main folder must also be replaced. Additionally all plugins need to be replaced in adm_plugins folder. If you previously haven't used any plugin, you should copy the folder adm_plugins to your installation, as our default theme used this.
As a final step you must now call the index.php in the main folder with your browser. This guides you to the update dialog. For security reasons you need to insert username and password of a webmaster. Now you can update the database to version 3.
You have successfully updated Admidio to version 3 and you can now Update to version 4 from version 3.x.