How to uninstall Drupal 8 module when uninstall page returns 500 http error?

I ran your Select statement on my database, at the mysql command line, and saw the json response with the 'error-generating module' listed.  But how do I 'pluck' it out?  If the answer is dump it to a file, edit, and set database record to the contents of the edited file.  The dump and insert commands for the file would be helpful.  Thank you.

Been struggling with a broken D8 site (including admin UI) and after hours of search, your comment has been a life saver. In my case, the offending module was something called 'datetime'. I found references to it in both the ‘cache_config’ and ‘config’ tables:

s:8:"datetime";i:0;

So I removed the string and uploaded the edited blob (using TextEdit on Mac) back to the respective tables. This finally solved the PHP error relating to datetime, but I have a different error now:

[16-Jul-2020 09:26:30 Asia/Kolkata] Uncaught PHP Exception Drupal\Component\Plugin\Exception\PluginNotFoundException: "The "node" entity type does not exist." at /home/username/public_html/core/lib/Drupal/Core/Entity/EntityTypeManager.php line 133

Is there something about the string I removed that could be causing this new error?

Only problem with that is it's serialized data, so if you just remove the string, you didn't update the count on the array (e.g. before it would have been like a:155 and after you removed it, it should be a:154). It's best to unserialize the data, make your changes, serialize it, and then save that.

If your site itself not broken and you are able to see normal pages. Then you can uninstall a broken module directly from database as suggested @joris_lucis using a custom module.

You can do it manually or you can simply create a custom module or add a controller to an existing module or write hook_update_n it is up to you to how do you want automate this process. 

In my case I have created a Controller into my existing module to uninstall the module completely from config table.

# Path web/modules/custom/boult/boult.routing.yml
boult.boult_schema:
  path: '/boult/schema'
  defaults:
    _controller: '\Drupal\boult\Controller\BoultController::repSalesforce'
    _title: 'Rep Salesforce'
  requirements:
    _permission: 'access content'

Then create a controller class

<?php

namespace Drupal\boult\Controller;

use Drupal\Core\Controller\ControllerBase;
use GuzzleHttp\Command\Guzzle\Deserializer;
use Symfony\Component\DependencyInjection\ContainerInterface;

/**
 * Class BoultController.
 */
class BoultController extends ControllerBase {

  /**
   * Drupal\Core\Database\Driver\mysql\Connection definition.
   *
   * @var \Drupal\Core\Database\Driver\mysql\Connection
   */
  protected $database;

  /**
   * {@inheritdoc}
   */
  public static function create(ContainerInterface $container) {
    $instance = parent::create($container);
    $instance->database = $container->get('database');
    return $instance;
  }

  /**
   * Remove broken module entry from config table.
   *
   * @return string
   *   Return Hello string.
   */
  public function repSalesforce() {
    // $query = "select data from config where name = 'core.extension'";
    $query = $this->database->select('config', 'c');
    $query->condition('c.name', 'core.extension')
      ->fields('c', ['data']);
    $result = $query->execute()
      ->fetchField();
    $arrayResult =  unserialize($result);
    foreach ($arrayResult['module'] as $key => $value) {
      // In my case module name is rep_mapping
      if ($key == 'rep_mapping') {
        unset($arrayResult['module']['rep_mapping']);
      }
    }
    $updated = serialize($arrayResult);

    $this->database
      ->update('config')
      ->fields(['data' => $updated])
      ->condition('name', 'core.extension')
      ->execute();

    return [
      '#type' => 'markup',
      '#markup' => $updated,
    ];
  }

}

Once you are done enable your module or clear cache for existing module. Now visit the url you have given in routing.yml file, in my case http://baseurl/boult/schema, to remove the entry from database. I hope this will help to avoid manual editing of blob file.

Thanks @joris_lucius,

It's works!!!

The other option is disable module using drush command, If drush is installed.
Command : "drush pm-uninstall module-name"