Ajax link flag does not work in view with ajax enabled.

6 years without any activity. I think we can close it as outdated. Please reopen if needed.

I am not sure how you tested this but I am seeing the exact same issue. I am trying to create a bookmark by code for groups. From what I see I should be able to just use a hook preprocess group then add the flag to the twig template.

After writing the code I ended up with the same results as the title of this issue:

Type page not found
Date Tuesday, March 11, 2025 - 13:54
Location https://localhost/flag/flag/bookmark/2860?_wrapper_format=drupal_ajax&de...
Referrer https://localhost/admin/reports/dblog/event/703
Message /flag/flag/bookmark/2860?_wrapper_format=drupal_ajax&destination=/customer/acquisition-service-fas&token=Yz12EQbsQsAf4Ro5JtQyYDUAAbO2mpC1en24tGZjt5A

I thought I would give more context around how this was replicated. I found that I can save a bookmark by writing out the save object. The problem seems to come from trying to create a link. The following is the code I'm using to create that link:

function [hook]_preprocess_group(&$variables){

$group = $variables['group'];

// add a flag link for bookmarks
$flag_link = [
'#lazy_builder' => ['flag.link_builder:build', [
'group', //also tried with $group->getEntityTypeId(),
$group->id(),
'bookmark',
]],
'#create_placeholder' => TRUE,
];
$variables['flag_link'] = $flag_link;

This creates the link from the template by using {{ flag_link }}. After clicking on that link however I get the error described on this issue. I found that if I create my own save it seems to save the flag just fine with the following code:

$flag = \Drupal\flag\Entity\Flag::create([
'id' => $group->id(),
'entity_type' => 'group',
'bundles' => [
'customer',
],
'flag_type' => 'entity:group',
'link_type' => 'reload',
'flagTypeConfig' => [],
'linkTypeConfig' => [],
]);
$flag->save();

So it would seem if I want to bypass this issue I'll have to create my own links to save and remove. I hope this helps debug the issue for others.

Having updated from 8.x-4.0-beta5 to 8.x-4.0-beta6, we've started seeing this.

We do have a patch applied for ✨ Allow AjaxResponse to be altered RTBC - possibly related?

Looking at the difference between beta5 and beta6, one significant difference seems to be the changes in flag.routing.yml

The patch on 🐛 Compatibility with Flag 8.x-4.0-beta6 Active solved the problem for us.