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Troubleshooting

Important

MongoDB 8.2 is the latest minor release. Starting with MongoDB 8.2, minor releases are available for on-premises deployments (MongoDB Community and Enterprise) for specific use cases. For more information, see MongoDB Versioning.

To install the latest MongoDB version supported for on-premises use, see the installation instructions.

Public Key Retrieval Errors

Occurs during the Import the public key used by the package management system step of Install MongoDB Community Edition.

gpg: no valid OpenPGP data found.

Solution

Copy the command exactly as documented. The operation should respond with OK.

Verify that the MongoDB public GPG key exists on your system:

sudo apt-key list

Expected output resembles the following:

/etc/apt/trusted.gpg
--------------------
pub   rsa4096 2018-04-18 [SC] [expires: 2023-04-17]
      E162 F504 A20C DF15 827F  718D 4B7C 549A 058F 8B6B
uid           [ unknown] MongoDB 8.0 Release Signing Key <packaging@mongodb.com>

sudo apt update Errors

Occurs after running sudo apt update as part of the Install MongoDB Community Edition procedure. Often caused by a missing MongoDB Public GPG key.

W: GPG error: https://repo.mongodb.org/apt/ubuntu <release>/mongodb-org/8.2 Release: \
   The following signatures couldn't be verified because the public key is not available: NO_PUBKEY 4B7C549A058F8B6B
E: The repository 'https://repo.mongodb.org/apt/ubuntu <release>/mongodb-org/8.2 Release' \
   is not signed.
N: Updating from such a repository can't be done securely, and is therefore disabled by default.
N: See apt-secure(8) manpage for repository creation and user configuration details.

Solution

Repeat the Import the public key used by the package management system step in Install MongoDB Community Edition. Copy the command and key exactly as documented.

Verify the key:

sudo apt-key list

Expected output:

--------------------
pub   rsa4096 2018-04-18 [SC] [expires: 2023-04-17]
      E162 F504 A20C DF15 827F  718D 4B7C 549A 058F 8B6B
uid           [ unknown] MongoDB 8.0 Release Signing Key <packaging@mongodb.com>

sudo apt install -y mongodb-org Errors

Occurs after running sudo apt install -y mongodb-org in step Create a list file for MongoDB of the Install MongoDB Community Edition procedure. Often caused by a missing or misconfigured /etc/apt/sources.list.d/mongodb-org-8.2.list file.

Reading package lists... Done
Building dependency tree
Reading state information... Done
E: Unable to locate package mongodb-org

Solution

  1. Check the file contents:

    cat /etc/apt/sources.list.d/mongodb-org-8.2.list

  2. If contents don't match the documentation for your Ubuntu version, remove the file and repeat Create a list file for MongoDB step.

  3. If the file doesn't exist, create it during that step.

  4. Update repositories and retry installation:

    sudo apt update
    sudo apt install -y mongodb-org

dpkg-deb: error Package Conflicts

Occurs during sudo apt install -y mongodb-org step of the Install MongoDB Community Edition procedure. Often caused by a conflicting Ubuntu mongodb package already installed.

dpkg: error processing archive /var/cache/apt/archives/mongodb-org-server_8.2.0_amd64.deb (--unpack):
trying to overwrite '/usr/bin/mongod', which is also in package mongodb-server-core 1:3.6.3-0ubuntu1

Solution

Check for conflict:

sudo apt list --installed | grep mongo
mongodb/bionic,now 1:3.6.3-0ubuntu1 amd64 [installed]
mongodb-clients/bionic,now 1:3.6.3-0ubuntu1 amd64 [installed,automatic]
mongodb-server/bionic,bionic,now 1:3.6.3-0ubuntu1 all [installed,automatic]
mongodb-server-core/bionic,now 1:3.6.3-0ubuntu1 amd64 [installed,automatic]

If output shows Ubuntu packages like this, remove them:

sudo apt remove mongodb
sudo apt purge mongodb
sudo apt autoremove

Note

sudo apt purge mongodb removes default configuration files. To preserve modified configuration files, copy them to another directory (e.g., /home/your-user-name) before purging.

For mixed packages:

If output shows both mongodb-org and mongodb packages, remove mongodb-org first, then remove mongodb packages. After clearing all MongoDB-related packages, retry Install MongoDB Community Edition.

mongod Socket Errors

Occurs when starting a mongod. Often caused by another process (typically another mongod) using the configured port.

Socket is already in use
Failed to unlink socket file

Solution

Identify the process:

The following example uses ss to list all open TCP (-t) and UDP (-u) sockets in the LISTEN (-l) state and the process using each socket (-p) without resolving any service names or hostnames (-n):

sudo ss -tulpn

Example output showing mongod on port 27017:

Netid        State        Local Address:Port
udp          UNCONN       127.0.0.53%lo:53        users:(("systemd-resolve",pid=663,fd=12))
udp          UNCONN   10.1.16.87%enp0s3:68        users:(("systemd-network",pid=652,fd=15))
tcp          LISTEN       127.0.0.53%lo:53        users:(("systemd-resolve",pid=663,fd=13))
tcp          LISTEN             0.0.0.0:22        users:(("sshd",pid=819,fd=3))
tcp          LISTEN        192.168.1.15:27017     users:(("mongod",pid=10027,fd=12))
tcp          LISTEN           127.0.0.1:27017     users:(("mongod",pid=10027,fd=11))
tcp          LISTEN                 ::]:22        users:(("sshd",pid=819,fd=4))

You can either:

  • Shut down the existing process

  • Select a new port for the conflicting mongod process:

    1. Modify net.port in the configuration file

    2. Use --port on the command line

Data Directory Errors

Occurs in the mongod process log. Often caused by a data directory that doesn't exist or isn't accessible to the mongod.

Data directory ... not found
Attempted to create lock file on a read-only directory: ...

When starting as a service (sudo systemctl start mongod or sudo service mongod start), this may mean:

  • dbPath in /etc/mongod.conf points to a directory without rwx permissions for mongodb user or group

  • dbPath points to a nonexistent directory

When starting from the terminal, this may mean:

  • dbPath or --dbpath points to a directory without rwx permissions for the user or their group

  • The Directory doesn't exist

Solution

Depending on the cause, either create the data directory or set appropriate permissions and ownership.

  • Create the directory:

    Specify the data directory with storage.dbPath in the configuration file or --dbpath on the command line.

  • Set default paths:

    Ensure that the data directory exists or create the directory using mkdir before starting mongod.

  • Set directory permissions:

    Set appropriate permissions and ownership:

    • The mongod needs rwx (read, write, execute) permissions

    • Use chown and chmod to configure user:group ownership and permissions prior to starting the mongod

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