Troubleshooting

When you install/uninstall a module there is usually an error if the module code removed but its entry exist in DB. Some time both exists but still this error. The full error is : 

the following module is marked as installed in the core.extension configuration, but it is missing:

Solution:

Using PMA run the following SQL to fix it.

delete from `key_value` where collection = 'system.schema' and name = 'image_downloader';

This error occurs in ctools.

Converting back to version 3.9.0 solved it.

composer require 'drupal/ctools:3.9.0'

During my earlier days with Drupal module development, the instructor gave these instructions  with a smiley face that more than 90% of drupal issue are related to Drupal cache.

Since then I was paying special attention to it while module development but today I spent a couple of hours & googling around, looking at different logs & debugging & turning stones here and there, beating around the bushes to solve the following problem:

Exception: Serialization of 'Symfony\Component\HttpFoundation\File\UploadedFile' is not allowed in serialize() (line 14 of /opt/web/core/lib/Drupal/Component/Serialization/PhpSerialize.php).

And a million dollar solution is to add the following in the build method.

 // Don't cache
 $form_state->disableCache();

This error occurs while enabling a module in extend.

The solution is :

docker exec -ti container_name composer update
docker exec -ti container_name chmod 777 /opt -Rf
docker exec -ti container_name /opt/vendor/drush/drush/drush cr

While updating composer packages (specially using docker) you may encounter memory limit reached issue. The solution is to simply run the composer update command on localhost (without docker container), and may be install (composer.json packages) it in docker then.

Enable components module

Check for user permissions

The composer.lock is a directory, remove it an run composer install again.