Hello,
I'm having the exact same problem here. I've tried changing localhost for my IP address on config.json and I'm still having the same error.

here's my config.json file:
{
"url": "http://my.ip.adress:4567",
"secret": "xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxx",
"database": "mongo",
"mongo": {
"host": "127.0.0.1",
"port": "27017",
"username": "nodebb",
"password": "nodebb",
"database": "nodebb"
}
}

Do you guys have any idea on what is happening?