I started the Mercure hub with this command on Windows10 :

mercure --jwt-key="eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJtZXJjdXJlIjp7InB1Ymxpc2giOltdfX0.Oo0yg7y4yMa1vr_bziltxuTCqb8JVHKxp-f_FwwOim0" --addr="localhost:3000" --allow-anonymous --cors-allowed-origins="*"

The hub run successfully

I want to publish updates from Symfony :

In the .env file there is :

###> symfony/mercure-bundle ###
# See https://symfony.com/doc/current/mercure.html#configuration
MERCURE_PUBLISH_URL=http://localhost:3000/.well-known/mercure
# The default token is signed with the secret key: !ChangeMe!
MERCURE_JWT_TOKEN=eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJtZXJjdXJlIjp7InB1Ymxpc2giOltdfX0.Oo0yg7y4yMa1vr_bziltxuTCqb8JVHKxp-f_FwwOim0
###< symfony/mercure-bundle ###

In the lexik_jwt_authentication.yaml :

lexik_jwt_authentication:
    secret_key: '%env(resolve:JWT_SECRET_KEY)%'
    public_key: '%env(resolve:JWT_PUBLIC_KEY)%'
    pass_phrase: '%env(JWT_PASSPHRASE)%'
    token_ttl: '%env(JWT_TOKEN_TTL)%'
    user_identity_field: username

Then in the Symfony :

/**
     * @RestPost("/api/insertUpdateSynonyms", name ="api_insert_update_synonyms")
     * @RestRequestParam(name="old_cle", nullable=true)
     * @RestRequestParam(name="add_synonymes", nullable=true)
     * @RestRequestParam(name="new_cle", nullable=true)
     * @RestRequestParam(name="new_synonymes", nullable=true)
     *
     * @return JsonResponse
     */
    public function insertUpdateSynonyms(ParamFetcher $paramFetcher, SearchService $searchService, PublisherInterface $publisher)
    {
        try {
            $retour = $searchService->insertUpdateSynonyms($paramFetcher);
            $update = new Update(
                'http://bdc.pulse.mg/notif/suggestioncontenu',
                json_encode(['msg' => '============================= new content updated ! ................................'])
            );
            $publisher($update);
        } catch (Exception $e) {
            $retour = array('error' => array('error_code' => $e->getCode(), 'message' => $e->getMessage()));
        }
        $response = new JsonResponse();
        $response->setData($retour);
        return $response;
    }

In the Angular side :

insertSynonyme(){
    const data = {
      old_cle: this.synoForm.value.cle_syno,
      add_synonymes: this.dataSynonyme.oldSynonyme
    };
    this.generalServ.insertSynonyme(data).subscribe( 
      res => {
        const eventSource = new EventSource('http://localhost:3000/.well-known/mercure?topic=' + encodeURIComponent('http://bdc.pulse.mg/notif/suggestioncontenu'));
    eventSource.onmessage = function (event) {
      // Will be called every time an update is published by the server
      console.log("============== avant show data de leventsource");
      console.log(JSON.parse(event.data));
    }
        if(res.code === 200){
          this.toastr.success('Sent');
          this.submitted = true;
          // this._document.defaultView.location.reload();
        }
      });
  }

At runtime the console shows nothing

Even if I replace the MERCURE_JWT_TOKEN to eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJtZXJjdXJlIjp7InB1Ymxpc2giOlsiKiJdfX0.iHLdpAEjX4BqCsHJEegxRmO-Y6sMxXwNATrQyRNt3GY , and I start the hub with the command : mercure --jwt-key="eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJtZXJjdXJlIjp7InB1Ymxpc2giOlsiKiJdfX0.iHLdpAEjX4BqCsHJEegxRmO-Y6sMxXwNATrQyRNt3GY" --addr="localhost:3000" --allow-anonymous --cors-allowed-origins="*" , then nothing is displayed in the console.

Here is hub log :

127.0.0.1 - - [09/Dec/2020:16:54:50 +0300] "GET /.well-known/mercure?topic=http%3A%2F%2Fbdc.pulse.mg%2Fnotif%2Fsuggestioncontenu HTTP/1.1" 200 8 "http://localhost:4300/" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.88 Safari/537.36"
time="2020-12-09T16:55:48+03:00" level=info msg="New subscriber" last_event_id= remote_addr="127.0.0.1:57682" subscriber_id="urn:uuid:95346ec2-44f0-40f6-b80e-8bc0a8c9649e" subscriber_topics="[http://bdc.pulse.mg/notif/suggestioncontenu]"
time="2020-12-09T16:56:43+03:00" level=info msg="Subscriber disconnected" last_event_id= remote_addr="127.0.0.1:57682" subscriber_id="urn:uuid:95346ec2-44f0-40f6-b80e-8bc0a8c9649e" subscriber_topics="[http://bdc.pulse.mg/notif/suggestioncontenu]"
127.0.0.1 - - [09/Dec/2020:16:55:48 +0300] "GET /.well-known/mercure?topic=http%3A%2F%2Fbdc.pulse.mg%2Fnotif%2Fsuggestioncontenu HTTP/1.1" 200 8 "http://localhost:4300/" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.88 Safari/537.36"
time="2020-12-09T16:56:46+03:00" level=info msg="New subscriber" last_event_id= remote_addr="127.0.0.1:57682" subscriber_id="urn:uuid:991175e2-d0e3-43b3-bb83-87ab4a475f1a" subscriber_topics="[http://bdc.pulse.mg/notif/suggestioncontenu]"
time="2020-12-09T16:57:41+03:00" level=info msg="Subscriber disconnected" last_event_id= remote_addr="127.0.0.1:57682" subscriber_id="urn:uuid:991175e2-d0e3-43b3-bb83-87ab4a475f1a" subscriber_topics="[http://bdc.pulse.mg/notif/suggestioncontenu]"
127.0.0.1 - - [09/Dec/2020:16:56:46 +0300] "GET /.well-known/mercure?topic=http%3A%2F%2Fbdc.pulse.mg%2Fnotif%2Fsuggestioncontenu HTTP/1.1" 200 8 "http://localhost:4300/" "Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/87.0.4280.88 Safari/537.36"
time="2020-12-09T16:57:44+03:00" level=info msg="New subscriber" last_event_id= remote_addr="127.0.0.1:59691" subscriber_id="urn:uuid:1d18280a-2bf2-4242-b7d6-591c01abc8af" subscriber_topics="[http://bdc.pulse.mg/notif/suggestioncontenu]"
time="2020-12-09T16:58:39+03:00" level=info msg="Subscriber disconnected" last_event_id= remote_addr="127.0.0.1:59691" subscriber_id="urn:uuid:1d18280a-2bf2-4242-b7d6-591c01abc8af" subscriber_topics="[http://bdc.pulse.mg/notif/suggestioncontenu]"

So what is wrong ?

Source: Symfony4 Questions