Menu block is never empty, region keeps showing up

I'm experiencing this exact same issue. In ver 8.0.1 AND 8.0.2

Region markup generates, even if menu for that page is empty. In Durpal 7, if the menu was empty for that node, the region did not generated. That felt like the correct functionality.

I guess we need something like #2443457: Views block displayed when no results returned here.

Can it be caused by wrong visibility determination in a theme?

@Chi
Indeed this might be possible.

Does someone have a workaround for this moment?

@michiellucas, I do
http://cgit.drupalcode.org/samara/tree/js/samara.js?h=8.x-1.x#n43

I am still facing this issue with Drupal 8.1.0 :(
region|render workaround works only with Twig debug disabled.

Still same problem with Drupal 8.2.5, anyone have solution?

This still appears to be an issue in 8.3.x and 8.4.x-dev.

1. Install core with Standard profile
2. Create six basic pages arranged on the main navigation menu so that 1, 3, and 5 are on menu root, 2 and 4 are subs of 1 and 3 respectively (page 6 intentionally not on menu).
3. Create a menu block with Initial visibility level set to 2, and levels to display unlimited. Place this block in Featured Top (the only empty default region, and helpfully with a grey background.
4. View all 6 pages, and you will see the menu correctly when it should be there, and an empty grey bar on remaining pages.

I'm getting this too with 8.3.2

Is everyone using the Menu Block module in contrib? I'm currently using Drupal 8.3.3 and ran into this issue, however was also using Menu Block for additional functionality. I disabled that module and the core block functionality worked as expected. Seems to be a known issue with Menu Blocks: https://www.drupal.org/node/2757215.

As @acrosman mentioned, simply create a menu block with a visibility lower on the tree than available menu items and visit a page with the region. The output is an empty string and therefore rendered as such. This issue persists in 8.3.5 (my current version)

Workaround:
Add a condition to your twig file

{% if page.region_name.block_machine_name|render is not same as('') %}
  {{ page.region_name }}
{% endif %}

This is very undesirable as you'd have to repeat this for each instance of a menu block.

Note: not using menu_block module

If like me you were experiencing this issue while using the Book Navigation Block with the setting "Show block only on book pages", and it is the only Block in the region, then a workaround is to set the Content Types in the Book Navigation Block Settings to only the Content Types that the menu is actually used on. Doing that seems to have solved the problem for me!

I'm seeing this issue too. We do have menu block attached but judging from the investigation I've done and reading through the last comments I don't think it's related.

This issue predates Big Pipe in core, so probably a different cause, but region markup may still be output if blocks output placeholders that are then replaced with an empty string by Big Pipe. One solution in that case is to use the block's access method to control block visibility, instead of returning an empty string from the block's render method (#953034-305: [meta] Themes improperly check renderable arrays when determining visibility)

This issue seems to be global with block behaviour, not just the menu block. It concerne all empty blocks displayed in regions.
There is few related discussions about this topic:
The main I find is https://www.drupal.org/node/953034
https://drupal.stackexchange.com/questions/175389/how-do-i-properly-dete...
https://drupal.stackexchange.com/questions/198052/hide-region-when-block...
https://www.drupal.org/forum/support/module-development-and-code-questio...

#17 works for me for book navigation block. Thanks!

FYI I believe this works to hide regions if a block is empty. (you have to put this code in a .module file in a custom module.)

<?php

use Drupal\block\Entity\Block;
use Drupal\Core\Access\AccessResult;
use Drupal\Core\Session\AccountInterface;

/**
 * Implements hook_block_access().
 */
function mymodule_block_access(Block $block, $operation, AccountInterface $account) {
  if ($operation === 'view') {
    $block = Block::load($block->id());
    $block_content = \Drupal::entityTypeManager()
      ->getViewBuilder('block')
      ->view($block);
    $markup = \Drupal::service('renderer')->renderRoot($block_content);
    return AccessResult::forbiddenIf($markup === '')->addCacheableDependency($block);
  }
  return AccessResult::neutral();
}

Probably not the greatest solution, because you have to render the block to check if it is empty before it renders again to be output in your theme.

Closing as cannot reproduce

Tested on Drupal 9.5
Created an empty menu
Placed that menu in a block region
Verified nothing was rendering.

If you still feel this is an issue please reopen with the steps you are seeing them in.

Create a menu with submenu items.
Create a menu_block.
- Initial visibility level: 2
- Number of levels to display: unlimited
Place menu_block in sidebar_first.

On pages where there are no submenu items available (i.e. homepage) sidebar_first is shown.

The problem exists in 9.5.9.

Patches that did not work:
- https://www.drupal.org/project/menu_block/issues/3271218 (both patches)
- https://raw.githubusercontent.com/stef-van-looveren/drupal-8-patches/mas...

This one is working, but keep in mind that if twig_debug = true, the sidebar_left is shown:
https://www.drupal.org/project/menu_block/issues/3007225

There is no patch to review.

Needs an issue summary update and will need tests

Also can you test with just core modules. If this is triggered by menu block could be bug there