Weaver II Pro is 100% upward compatible with the Weaver II Free version. All of your settings will be preserved in the WordPress database. As usual, however, it is always a good idea to save your settings before upgrading – use the Save/Restore tab to save a full backup version of your settings on your own computer.

But there can be a couple of issues during the transition. Weaver II Pro and Weaver II Free are two different themes. Since about WordPress 3.4, WordPress has changed how it handles some things when you switch from one theme to a different one. No content or settings are lost, but you may have to re-select a couple of things.

1. WordPress will “forget” what header image you’ve set for one theme to the next. So, you may have to open the Dashboard -> Appearance -> Header setting, and re-select your previous header.
2. WordPress will “forget” the background image as well. Same story, simply open the Background admin page and re-select your previous background image.
3. WordPress will also “forget” which custom menus you’ve assigned to any menu areas. The menu definitions themselves remain intact – it is just which menus you may have assigned to Primary Navigation, Mobile Navigation, or Secondary Navigation in the custom menu Manage Locations tab will need to be reset. If you don’t have any custom menus, then nothing needs to be reset.
4. WordPress can also “forget” which widgets you’ve put in which widget area when you switch themes. Fortunately, this process is a bit different, and since both versions of Weaver II use the same names, widget assignments are usually not lost. If you switch to a third theme in between, it is possible to lose the widget assignments. In that event, your widgets will be saved in the “Inactive Widgets” box on the Widgets admin page, so you won’t lose any custom widget contant you may have created.

Note – if you switch between Weaver II and Aspen, the same situation applies – you may need to re-select header, background, and menu locations.

If you switch from Weaver II Pro back to Weaver II Free and save settings, some Pro settings will be preserved, and some will be lost. Always backup your theme settings if you switch back to Weaver II Free from Pro.