@shakthydoss回答工作得很好，但在第二个问题后。lock不在那里，我只是创建了一个空白的，它工作得很好。所以检查一下你的是否在那里。

如果您正在使用命令行:

cd /var/lib/mongodb

ls

“ls”将列出该文件夹中的所有文件，如果mongod. exe文件被删除。锁不在那里，那么:

sudo touch mongod.lock

最后运行命令。

mongod –-repair

sudo service mongod start 

Mongo服务应该工作正常。

我的原因是空间-在控制台运行这个:

df -h

或者更具体地说:

du -hs /var/lib/mongodb/ 

检查磁盘使用情况。如果它是~ 99% -只是清理一些空间，再试一次!

Resolved. This problem could be solved by the below mentioned 4 steps 1) Remove .lock file sudo rm /var/lib/mongodb/mongod.lock 2) repair the mongodb mongod -–repair 3) start the mongod server sudo service mongod start 4) start the mongo client mongo For more details take a look at http://shakthydoss.com/error-couldnt-connect-to-server-127-0-0-127017-srcmongoshellmongo-js-exception-connect-failed/ http://shakthydoss.com/technical/error-couldnt-connect-to-server-127-0-0-127017-srcmongoshellmongo-js-exception-connect-failed/

要连接mongo，我们必须首先启动“mongod”服务。 您可以看到以下输出:

$ mongod
2017-03-05T00:31:39.055+0530 I CONTROL  [initandlisten] MongoDB starting : pid=1481 port=27017 dbpath=/data/db 64-bit host=Prabhu-Nandans-Mac.local
2017-03-05T00:31:39.056+0530 I CONTROL  [initandlisten] db version v3.4.2
2017-03-05T00:31:39.056+0530 I CONTROL  [initandlisten] git version: 3f76e40c105fc223b3e5aac3e20dcd026b83b38b
2017-03-05T00:31:39.056+0530 I CONTROL  [initandlisten] OpenSSL version: OpenSSL 1.0.2k  26 Jan 2017
2017-03-05T00:31:39.056+0530 I CONTROL  [initandlisten] allocator: system
2017-03-05T00:31:39.056+0530 I CONTROL  [initandlisten] modules: none
2017-03-05T00:31:39.056+0530 I CONTROL  [initandlisten] build environment:
2017-03-05T00:31:39.056+0530 I CONTROL  [initandlisten]     distarch: x86_64
2017-03-05T00:31:39.056+0530 I CONTROL  [initandlisten]     target_arch: x86_64
2017-03-05T00:31:39.056+0530 I CONTROL  [initandlisten] options: {}
2017-03-05T00:31:39.056+0530 W -        [initandlisten] Detected unclean shutdown - /data/db/mongod.lock is not empty.
2017-03-05T00:31:39.057+0530 I -        [initandlisten] Detected data files in /data/db created by the 'wiredTiger' storage engine, so setting the active storage engine to 'wiredTiger'.
2017-03-05T00:31:39.057+0530 W STORAGE  [initandlisten] Recovering data from the last clean checkpoint.
2017-03-05T00:31:39.057+0530 I STORAGE  [initandlisten] wiredtiger_open config: create,cache_size=3584M,session_max=20000,eviction=(threads_max=4),config_base=false,statistics=(fast),log=(enabled=true,archive=true,path=journal,compressor=snappy),file_manager=(close_idle_time=100000),checkpoint=(wait=60,log_size=2GB),statistics_log=(wait=0),
2017-03-05T00:31:39.620+0530 I CONTROL  [initandlisten] 
2017-03-05T00:31:39.620+0530 I CONTROL  [initandlisten] ** WARNING: Access control is not enabled for the database.
2017-03-05T00:31:39.620+0530 I CONTROL  [initandlisten] **          Read and write access to data and configuration is unrestricted.
2017-03-05T00:31:39.620+0530 I CONTROL  [initandlisten] 
2017-03-05T00:31:39.620+0530 I CONTROL  [initandlisten] 
2017-03-05T00:31:39.620+0530 I CONTROL  [initandlisten] ** WARNING: soft rlimits too low. Number of files is 256, should be at least 1000
2017-03-05T00:31:39.643+0530 I FTDC     [initandlisten] Initializing full-time diagnostic data capture with directory '/data/db/diagnostic.data'
2017-03-05T00:31:39.643+0530 I NETWORK  [thread1] waiting for connections on port 27017
2017-03-05T00:31:40.008+0530 I FTDC     [ftdc] Unclean full-time diagnostic data capture shutdown detected, found interim file, some metrics may have been lost. OK
2017-03-05T00:32:03.832+0530 I NETWORK  [thread1] connection accepted from 127.0.0.1:49806 #1 (1 connection now open)
2017-03-05T00:32:03.833+0530 I NETWORK  [conn1] received client metadata from 127.0.0.1:49806 conn1: { application: { name: "MongoDB Shell" }, driver: { name: "MongoDB Internal Client", version: "3.4.2" }, os: { type: "Darwin", name: "Mac OS X", architecture: "x86_64", version: "16.4.0" } }
2017-03-05T00:32:08.376+0530 I -        [conn1] end connection 127.0.0.1:49806 (1 connection now open)

然后打开另一个终端，输入“mongo”。

输出如下:

$ mongo
MongoDB shell version v3.4.2
connecting to: mongodb://127.0.0.1:27017
MongoDB server version: 3.4.2

你的问题解决了:)

如果以上方法都不奏效:进入service (start>search>services)，启动mongodb服务。然后，在cmd提示符中，进入bin后，键入:/>mongo

错误:无法连接到127.0.0.1:27017服务器，连接尝试失败:SocketException:错误连接到127.0.0.1:27017::导致::没有连接可以建立，因为目标机器主动拒绝它。

这个错误是因为Mongo服务器被关闭

遵循以下步骤

打开任务管理器 进入>服务 找到MongoDB 右键单击并选择Start