Verify you have enough resources to run MongoDB.

Check to see if you need to repair the database.

Verify that Apache is running.

Check the Mongo logs to reveal issues.

By default, MongoDB creates the Windows log file at this path:

C:\xampp\mongodb\bin\log\mongodb.log

By default, MongoDB creates the Linux log file at this path:

/var/log/mongodb/mongodb.log

If the log file is not found, then check the MongoDB config file for the location.

A connect command to get to the server fails.

For example:

[root@xxxx bin]# ./mongo MongoDB shell version: 

2.0.1 connecting to: test Mon Oct 31 18:41:32 

Error: couldn't connect to server 127.0.0.1 

shell/mongo.js:84 exception: connect failed

1. Verify that MongoDB server is running.

Try to open this in your web browser:
http://localhost:27017

If you can't, this means that you have to start MongoDB server.

2. Ensure all paths to the MongoDB server are absolute.

An absolute or full path points to the same location in a file system, regardless of the current working directory. To do that, it must include the root directory.

3. Add your server IP to the Bind list.

Open the file /etc/mongod.conf

Find the bind_ip line

Add the IP address of the machine from where you are connecting

bind_ip = 127.0.0.1, your Remote Server Machine IP Address Here

For example:

bind_ip = 127.0.0.1,192.168.1.5

Then restart mongodb service:

sudo service mongod restart

Make sure mongodb port is opened in the firewall.

You can also comment the line, if you are not worried about security.

4. Verify you are running MongoDB as root user.
If you are getting something similar to the following message:

start: Rejected send message, 1 matched rules; type="method_call", 

sender=":1.86" (uid=1000 pid=3215 comm="start mongodb ") 

interface="com.ubuntu.Upstart0_6.Job" member="Start" error 

name="(unset)" requested_reply="0" destination="com.ubuntu.Upstart" 

(uid=0 pid=1 comm="/sbin/init")

tester@TesterPC:/var/lib/mongodb$ mongosh

You must be trying to start the mongodb service as user other than root. You must be root user.

Log in as root and then run following command:

sudo bash

followed by

service mongodb start

5. Remove a full mongod.lock file.

Check if the following file exists:

/var/mongo/mongod.lock exists

If it exists, check to see if it has content.

If it is not empty, then remove the file.

Then restart MongoDB.

service mongodb start

6. Check the Mongo logs to reveal other issues

By default, MongoDB creates the Windows log file at this path:

C:\xampp\mongodb\bin\log\mongodb.log

By default, MongoDB creates the log file at this path:

/var/log/mongodb/mongodb.log

If the log file is not found, then check the MongoDB config file for the location.

For example, other connection issues can include:

Wed Dec 21 03:35:04 [initandlisten] 
connection refused because too many open connections: 819

By default, FileCloud installs the Mongo database server on the same machine as the webserver without any authentication settings.

If you need to enable authentication for added security or if you are hosting the database on a different machine than the web server, then these settings can cause this backup error if they are not configured correctly.

For more information, read the MongoDB Manual on Backup

1 Verify whether MongoDB Authentication is Enabled. If it is, ensure the settings are correct, or disable authentication to troubleshoot the backup error.

Enable MongoDB Bind IP and Authentication

2. Ensure all paths to the MongoDB server are absolute.

An absolute or full path points to the same location in a file system, regardless of the current working directory. To do that, it must include the root directory.

Host String refers to the URI format used for defining connections between applications and MongoDB instances.

The format is the same for all official MongoDB drivers.

mongodb://[username:password@]host1[:port1][,host2[:port2],...[,hostN[:portN]]][/[database][?options]]

host1 parameter is required. It identifies a server address to connect to. It identifies either a hostname, IP address, or UNIX domain socket.

For more information, read the MongoDB Manual on

the Standard Connection String Format

If you see this error, then either the host1 parameter is not specified correctly or the server address is not available.

1. Check the Mongo logs to inspect the host1 parameters.

By default, MongoDB creates the Windows log file at this path:

C:\xampp\mongodb\bin\log\mongodb.log

By default, MongoDB creates the log file at this path:

/var/log/mongodb/mongodb.log

If the log file is not found, then check the MongoDB config file for the location.

2. Verify the host1 parameters are correct:

• hostname and IP address
• or UNIX domain socket

3. Verify that host1 server is available.

4. Ensure all paths to the MongoDB server are absolute.

An absolute or full path points to the same location in a file system, regardless of the current working directory. To do that, it must include the root directory.

1. Run the correct version.

• Verify your MongoDB version meets the requirements in the Release Notes.

2. Remove incorrect versions.

• If you suspect that the Ubuntu mongodb package conflicts with the MongoDB Inc. mongodb-org package, then:

Run the following command to check if the mongodb package is already installed on the system.

sudo apt list --installed | grep mongodb

To completely remove and purge the mongodb package before attempting this procedure in FileCloud:

sudo apt remove mongodb 
sudo apt purge mongodb