are you sure that any of the service needed by onlyoffice are up and running?
this looks like rabbitmq, redis and postgres are not working.
[2019-11-17T14:10:25.421] [ERROR] nodeJS - [AMQP] Error: connect ECONNREFUSED 127.0.0.1:5672
[2019-11-17T14:00:00.112] [ERROR] nodeJS - sqlQuery error sqlCommand: SELECT * FROM task_result WHERE last_open_date <= : error: permission denied for relation task_result
[2019-11-17T14:10:22.314] [ERROR] nodeJS - redisClient error Error: Redis connection to localhost:6379 failed - connect ECONNREFUSED 127.0.0.1:6379
if your nextcloud instance is using also a selfsigned cert you have to tell onlyoffice to accept it. it’s explained here:thomass4t · GitHub