Drupal Solo Theme - How To Upgrade to Solo Theme - Part One

By the end of part one you will have every block from your current theme sitting in the right Solo region, without rebuilding the block layout by hand.

The tool that does the moving

Block placements belong to a theme. Switch theme and Drupal shows you an empty page, because none of your blocks are assigned to the new theme's regions. The Solo Copy Blocks module closes that gap: it reads every block entity assigned to the site's current default theme and recreates it against Solo. It runs from one button at /admin/config/system/solo-copy-blocks, and its own .info.yml lists ^10.1 || ^11 || ^12, the same core range as the Solo theme itself.

The order shown in the video

1. Install Solo but leave your existing theme as the default for now.
2. Install and enable Solo Copy Blocks.
3. Open Configuration → System → Copy Blocks to Solo Theme and press the button.
4. Read the confirmation message — it reports how many blocks were copied.
5. Check Block layout for Solo before you make Solo the default theme.

One thing to know before you press it: the module deletes the blocks already assigned to Solo, so a second run replaces rather than duplicates. Each copied block keeps its plugin, its settings, its visibility conditions, its weight and whether it was enabled or disabled, and the whole set is sorted by weight before it is written.

Region names that are translated on the way

Region machine names differ between the generations of this theme family, so a few are remapped explicitly rather than dropped:

• bottom_forth in W3CSS Theme becomes Solo's bottom_fourth.
• fixed_search_bar becomes fixed_search_block.
• The theme's Messages block lands in System Messages, and the Help block lands in Content.
• Anything whose region has no counterpart in Solo is parked in Footer Menu Container so it is never silently lost.

That last rule is why the review step matters — the parked blocks are exactly the ones you need to drag somewhere sensible.

Part two picks up from here: what the copy does not bring with it, and the settings you have to make yourself.

Want a Drupal theme built or customised around your brand rather than configured by hand? See Drupal theming services, or request a quote.