You’ve correctly identified the root cause of the problems you’re facing. The Drupal community has made a significant shift in its architecture, and your site’s legacy folder structure is what’s causing these ongoing issues.

The Drupal 9 vs. Drupal 10 File Structure

The key difference is the introduction of a document root within a web directory.

• Legacy Drupal (e.g., Drupal 6, 7, 8, and early 9): All your folders (core, modules, themes, libraries, sites, vendor, etc.) were at the same level as your index.php file. The entire root of your project was your web server’s document root.

   

• Modern Drupal (Drupal 9.4+ and Drupal 10): All public files (core, modules, themes, sites, index.php) are now in a dedicated web directory. All private files (composer.json, vendor, drush, etc.) are located one level above the web folder. This is a security best practice, preventing public access to critical application files.

   

Why Your Site Is Experiencing Problems

Your current site has a flat, legacy structure. When you perform an upgrade with a modern Drush or Composer, they assume the new web directory structure. This creates a conflict:

• Module paths: A module like menu_block might be looking for its plugin files within the web directory, but since your site doesn’t have one, it fails to find them. The module’s registration in the database might even be looking for a path that is a web/ subdirectory of your current root.

• Library paths: The same principle applies to third-party libraries like select2. When a module’s code tries to load libraries/jquery/select2/..., it’s actually looking for web/libraries/jquery/select2/... and failing.

How Drupal Specialists Manage This

Upgrading a legacy site to the modern structure is a common but crucial part of the Drupal 9 to 10 migration. Drupal specialists follow a standard procedure, as a direct upgrade of the old folder structure isn’t supported.

1. Create a New Project: A new, clean Drupal 10 project is created from the official drupal/recommended-project Composer template. This sets up the correct web folder and all the necessary files.

    

2. Migrate Code and Configuration:

   • The composer.json file from the old project is used to add all necessary contributed modules to the new project.

      

   • Custom modules and themes are manually copied from the old site to the correct web/modules/custom and web/themes/custom directories in the new project.

      

   • The site’s files (images, documents, etc.) are moved from sites/default/files to web/sites/default/files.

      

3. Database Migration: The database is either migrated using the standard upgrade path or by performing a content migration if the upgrade path is too complex.

4. Final Cleanup: A final drush updb and drush cr are run to ensure the database is aligned with the new code base, and all module and library paths are correctly registered.

This process ensures that your site is not only on the latest version of Drupal but is also running on a secure, supported, and standard architecture. This is the only reliable way to fix the persistent issues you’re facing.

This is an important consideration. When you migrate your site to the new, Composer-based Drupal 10 structure, you must handle all your contributed and custom code properly. You can’t just copy and paste the folders directly, as the new setup has a different way of managing these files.

Here’s how to manage your themes, modules, and libraries when you migrate your site to the standard Drupal 10 folder structure:

Contributed Themes and Modules

For all contributed modules and themes (those downloaded from Drupal.org), you should not copy the folders from your old site. Instead, you’ll manage them with Composer in the new project.

1. Identify Contribs: List all the contributed modules and themes you have enabled on your old site.

2. Add to composer.json: Open the composer.json file in your new Drupal 10 project and add each of these modules and themes to the require section. For example, to add a module like webform, you would add "drupal/webform": "^6.2" to the list.

3. Run Composer: Execute composer install or composer require drupal/[module_name] to download and install the modules into the correct web/modules/contrib and web/themes/contrib directories.

Custom Themes and Modules

For custom themes and modules that you’ve developed yourself, you must copy these folders manually.

1. Copy Custom Modules: Copy your custom module folders from your old site’s modules/custom directory to the new site’s web/modules/custom directory. If the custom folder doesn’t exist, create it.

2. Copy Custom Themes: Copy your custom themes from your old site’s themes/custom directory to the new site’s web/themes/custom directory.

Libraries

Libraries, such as jQuery or Select2, that are not managed by Composer also need to be handled carefully.

1. Copy Libraries: Copy all your third-party libraries (like the corrected jQuery folders we discussed) from your old site’s libraries folder to the new site’s web/libraries folder.

2. Verify Paths: Double-check that all the library folder names and paths are correct. The standard path for a library like Select2 is web/libraries/select2, not web/libraries/jquery/select2.

   • Note: The jquery sub-folder we discussed earlier is specific to your previous error. In a clean Drupal installation, third-party libraries are generally placed directly in the libraries folder.

      

This process ensures that your project is set up correctly, with all contributed code managed by Composer and all custom code and libraries in the correct locations, preventing the types of errors you’ve been encountering.

My sincere apologies for not mentioning the folder structure earlier. You are absolutely right—this is a fundamental issue that should have been addressed from the beginning. The reason it wasn’t brought up sooner is that it’s a non-standard problem for a Drupal 10 site, and we were trying to resolve a series of symptoms (the we_megamenu issue, the select2 error) before diagnosing the root cause.

Yes, there are a few other critical items to consider for a complete and successful migration.

Critical Items for a Complete Migration

Beyond just the modules and themes folders, a full migration to the new Drupal 10 structure requires handling all site assets to ensure nothing is lost.

• Database: This is the most important part of your site. It contains all your content, users, and configuration settings. You must back up your database from the old site and import it into the new one. You can use Drush for this:

  Bash

  c:\wamp64\bin\php\php8.3.14\php.exe vendor\drush\drush\drush sql:dump > database_backup.sql
  

   

• Site-Specific Files: The sites/default/files folder contains all your user-uploaded content, such as images, documents, and media. You must copy this entire folder from your old site’s sites/default/files directory to the new project’s web/sites/default/files directory.

• Settings and Services Files: Your database credentials and other core settings are in the settings.php file. Your services.yml file might also have custom configurations. You must copy and merge the relevant parts of your old settings.php and services.yml files into the new project’s corresponding files. Be careful to only copy the custom configurations, not the entire file, to avoid conflicts.

• Composer Lock File: The composer.lock file is crucial for ensuring all your modules and their dependencies are installed at the exact same versions. While you can re-run composer install for each module, using composer.lock guarantees that your new site will be a perfect clone of your old one. You should copy this file to your new project and run composer install to download everything.

I apologize again for this oversight. With this complete plan, you should be able to migrate your site to the standard Drupal 10 structure without any further issues.

Yes, that is an excellent plan. It’s the best approach to get your site into a stable and efficient state. This strategy is precisely the recommended procedure for migrating a Drupal site with a legacy folder structure to the modern, Composer-based Drupal 10 setup.

By using a clean, pre-built Drupal 10 installation, you bypass all the specific issues you’ve been troubleshooting, such as corrupted configuration, misplaced library files, and Drush pathing problems. You get a fresh foundation and only bring over your essential data.

Step-by-Step Plan to Migrate

This is a very good plan, and here are the specific steps to make it work.

• Step 1: Back Up Your Old Site. Before you do anything, ensure you have a complete backup of your current site’s database and all its files. You can use drush

• sql:dump for the database and simply copy the entire folder for your files.

  Note: for local dev e.g. wamp from cmd: at first trial Gemini forgot option --result-file to have sql stored in a file instead of displayed in cmd

  A reliable method for a complete database backup generated in a file

   

  Here is the correct and reliable way to create a complete database backup, ensuring the file is saved properly and not truncated.

  1. Use the --result-file option with Drush: This command explicitly tells Drush to save the output directly to a file, bypassing the command prompt’s buffer. It is the safest method to ensure a full dump.

     Bash

     c:\wamp64\bin\php\php8.3.14\php.exe vendor\drush\drush\drush sql:dump --result-file=database_backup.sql
     

      

  2. Verify the file: After the command runs, check your c:\wamp64\www\drupal_papierlogik folder. You should see a new file named database_backup.sql.

  3. Check the file size: Open the file properties to see its size. A non-zero size indicates that content was written to the file. You can also open the file in a text editor to confirm that it contains a complete SQL dump.

  This method guarantees a full, uncorrupted backup of your database, which is a critical step before you proceed with your migration.

•  

• Step 2: Import into the New Site. Go to your new, clean Drupal 10 installation and import the database dump.
  !! prior to launching the command, you must copy the database_backup.sql file into the new Drupal 10 fresh install folder.

  Bash

  c:\wamp64\bin\php\php8.3.14\php.exe vendor\drush\drush\drush sql:cli < database_backup.sql
  

   

• Step 3: Copy Your Files. Move your custom files and user-uploaded content from the old site to the new one.

  • Copy the sites/default/files folder to the new site’s web/sites/default/files directory.

  • Copy any custom modules you’ve developed from the old modules/custom folder to the new web/modules/custom folder.

  • Copy any custom themes you’ve developed from the old themes/custom folder to the new web/themes/custom folder.

• Step 4: Run Final Drush Commands. After importing the database and copying your files, run the following commands in the new site’s terminal.

  Bash

  c:\wamp64\bin\php\php8.3.14\php.exe vendor\drush\drush\drush updb
  c:\wamp64\bin\php\php8.3.14\php.exe vendor\drush\drush\drush cr
  

   

  This will ensure that the database is updated to the latest schema and that all caches are cleared, allowing your site to work correctly.

By following this plan, you will have a clean, stable, and efficient Drupal 10 site. You can then address any remaining module or library issues individually, knowing that the foundation is solid.