Elasticsearch 9.4.0 Basic authentication returns 401 Unauthorized

After upgrading from elasticsearch/kibana version 9.3.0 to elasticsearch/kibana 9.4.0 I'm no longer able to login with basic authentication via the Authorization Header.

This returns the error 401 Unauthorized.

{
"service": {
"version": "9.4.0",
"type": "kibana",
"state": "available",
"node": {
"roles": [
"background_tasks",
"ui"
]
},
"id": "X03JLrzKRxGOAfdABgkqoA"
},
"ecs": {
"version": "9.3.0"
},
"@timestamp": "2026-05-13T10:48:39.293+02:00",
"message": "Failed to activate user profile: {"error":{"root_cause":[{"type":"security_exception","reason":"unable to authenticate user [myuser_account] for action [cluster:admin/xpack/security/profile/activate]","header":{"WWW-Authenticate":["Basic realm=\"security\", charset=\"UTF-8\"","Bearer realm=\"security\"","ApiKey"]}}],"type":"security_exception","reason":"unable to authenticate user [myuser_account] for action [cluster:admin/xpack/security/profile/activate]","header":{"WWW-Authenticate":["Basic realm=\"security\", charset=\"UTF-8\"","Bearer realm=\"security\"","ApiKey"]}},"status":401}.",
"log": {
"level": "ERROR",
"logger": "plugins.security.user-profile"
},
"process": {
"pid": 121084,
"uptime": 163.995308519
},
"trace": {
"id": "bce5939754255e20e763798648dbe844"
},
"transaction": {
"id": "8fba08a59c0f9838"
}
}

{
"http": {
"response": {
"status_code": 401
},
"request": {
"method": "get",
"path": "/app/{id}/{any*}"
}
},
"error": {
"message": "security_exception\n\tRoot causes:\n\t\tsecurity_exception: unable to authenticate user [myuser_account] for action [cluster:admin/xpack/security/profile/activate]"
},
"service": {
"version": "9.4.0",
"type": "kibana",
"state": "available",
"node": {
"roles": [
"background_tasks",
"ui"
]
},
"id": "X03JLrzKRxGOAfdABgkqoA"
},
"ecs": {
"version": "9.3.0"
},
"@timestamp": "2026-05-13T10:48:39.293+02:00",
"message": "401 Unauthorized",
"log": {
"level": "ERROR",
"logger": "http"
},
"process": {
"pid": 121084,
"uptime": 163.995723184
},
"trace": {
"id": "bce5939754255e20e763798648dbe844"
},
"transaction": {
"id": "8fba08a59c0f9838"
}
}

Welcome to the forum @GeertVerbeurgt

Is this still an issue? If so, can you give a little bit more background here? You said you upgraded from 9.3.0 to 9.4.0, how precisely did you do that? Are you able to access your elasticsearch cluster at all? kibana at all? etc