我正在努力在RHEL 7.2上启动Rocket Chat服务器。它不断失败，并出现MongoDB错误“ MongoError：不是master和slaveOk = false”
版本详细信息：
mongod --version ==> db version v2.6.12
npm --version ==> 5.6.0
n --version ==> 2.1.12
node --version ==> v8.11.3
错误详细信息：
mongod: about to fork child process, waiting until server is ready for connections.
mongod: forked process: 25991
mongod: child process started successfully, parent exiting
systemd: Started High-performance, schema-free document-oriented database.
systemd: Started The Rocket.Chat server.
systemd: Starting The Rocket.Chat server...
rocketchat: /opt/Rocket.Chat/programs/server/node_modules/fibers/future.js:313
rocketchat: throw(ex);
rocketchat: ^
rocketchat: MongoError: not master and slaveOk=false
rocketchat: at queryCallback (/opt/Rocket.Chat/programs/server/npm/node_modules/meteor/npm-mongo/node_modules/mongodb-core/lib/cursor.js:233:23)
rocketchat: at /opt/Rocket.Chat/programs/server/npm/node_modules/meteor/npm-mongo/node_modules/mongodb-core/lib/connection/pool.js:532:18
rocketchat: at _combinedTickCallback (internal/process/next_tick.js:131:7)
rocketchat: at process._tickCallback (internal/process/next_tick.js:180:9)
systemd: rocketchat.service: main process exited, code=exited, status=1/FAILURE
systemd: Unit rocketchat.service entered failed state.
systemd: rocketchat.service failed.