The "entity:menu_link_content:main" plugin does not exist...

Thanks for STR. The error was reproduced.
I had attached the test coverage. So we need to fix the test.

I ran into a similar error when I tried to add a link to a programmatically created menu.

The menus are created with code something like this:

$collection_machine_name = 'subsite-50';
$menu = $this->entityTypeManager->getStorage('menu')->create([
  'langcode' => 'en',
  'status' => TRUE,
  'id' => $collection_machine_name,
  'label' => $collection->label() . ' subsite main navigation',
  'description' => 'Auto-generated menu for ' . $collection->label() . ' subsite',
]);
$menu->save();

When I try to save a link to the menu, I get the following.

Drupal\Component\Plugin\Exception\PluginNotFoundException: The "entity:menu_link_content:subsite-50" plugin does not exist

Clearing caches allows me to save links to the menu without further errors.

Since flushing all of the caches prevents the error, I looked through drupal_flush_all_caches() and, based on what happens in there, I found that the following can be run after a programmatically-created menu is saved:

\Drupal::service('cache.discovery')->deleteAll();
\Drupal::service('kernel')->rebuildContainer();

This prevents the PluginNotFoundException error from the TypedDataManager when I later try to add a menu link to the new menu.

We have a similar issue where we get this error if we create a new menu and then immediately use the the add link button. When we attempt to save the new link, we receive the Drupal\Component\Plugin\Exception\PluginNotFoundException. Likely similar to https://www.drupal.org/node/2773591 where we need cache emptied. Here is a small patch to do it if we have a menu insert.

I can confirm this happening here too. I also canconfirm flushing the caches fixes this.
To reproduce i created a new menu and directly tried to add a link.

I confirm the bug. The patch seems to fix it too, even if when creating a menu slow down a little bit the first link added, but we don't creat a menu every day. Thanks !

I had the same issue described above which the patch fixed. But unfortunately it's back elsewhere.

Steps:
I installed the patch, flushed cache, created menu items successfully, selected some view modes on the VM Settings tab, added an (existing) field and finally I got the error after selecting label: "Hidden" on the Manage Display page.

Error (white screen o' death):
Drupal\Component\Plugin\Exception\PluginNotFoundException: The "hidden" plugin does not exist. Valid plugin IDs for Drupal\Core\Field\FormatterPluginManager are: .....

I ran into this error, clearing the cache helped me get rid of the error

Please check if the latest patch works for you.
Thanks!

#15 works for me

@tolu_ thanks for the review!