Troubleshooting
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Errors when retrieving the public key
During the Import the public key used by the package management system
step of the Install MongoDB Community Edition procedure, you may
encounter a "gpg: no valid OpenPGP data found." error.
Ensure you are copying the command exactly as documented. The operation
should respond with OK.
To check that the MongoDB public GPG key exists on your system, run the following command in the terminal:
sudo apt-key list
The output should include an entry that 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>
Errors when running sudo apt update
You may encounter one or more errors that resemble the following
when running sudo apt-get update as part of the
Install MongoDB Community Edition procedure:
W: GPG error: https://repo.mongodb.org/apt/ubuntu <release>/mongodb-org/8.0 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/8.0 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.
These errors indicate that the MongoDB Public GPG key was not added in step Import the public key used by the package management system of the Install MongoDB Community Edition procedure.
Repeating the Import the public key used by the package management system step of the Install MongoDB Community Edition procedure typically resolves this issue. Ensure you are copying the command and key exactly as documented.
You can validate that the MongoDB public GPG key exists on your system by running the following command in the terminal:
sudo apt-key list
The output should include an entry that resembles the following:
-------------------- 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>
Errors when running sudo apt install -y mongodb-org
You may encounter an error that resembles the following when running
sudo apt install -y mongodb-org
in step Create a list file for MongoDB of the
Install MongoDB Community Edition procedure:
Reading package lists... Done Building dependency tree Reading state information... Done E: Unable to locate package mongodb-org
This error indicates that the
/etc/apt/sources.list.d/mongodb-org-8.0.list
may be configured incorrectly or is missing.
To review the contents of the mongodb-org-8.0.list file,
run the following command in the terminal or shell:
cat /etc/apt/sources.list.d/mongodb-org-8.0.list
If the file contents do not exactly match the documentation for your Ubuntu version in the step linked above, remove the file and repeat the Create a list file for MongoDB step. If the file does not exist, create it as part of that step.
Once you have validated that the mongodb-org-8.0.list
file exists and has the correct contents, run
sudo apt update to update the apt repositories and
retry sudo apt install -y mongodb-org.
Unable to install package due to dpkg-deb: error
You may encounter an error that resembles the following when
installing the mongodb-org package:
dpkg: error processing archive /var/cache/apt/archives/mongodb-org-server_8.0.0_amd64.deb (--unpack): trying to overwrite '/usr/bin/mongod', which is also in package mongodb-server-core 1:3.6.3-0ubuntu1
This error indicates that the system already had the Ubuntu
mongodb package installed prior to installing the official
MongoDB Inc. mongodb-org packages. To confirm wheter the
host has the Ubuntu mongodb package installed, run the
following command in a terminal or shell:
sudo apt list --installed | grep mongo
If your output resembles the following, you must uninstall
the Ubuntu mongodb package before retrying the
Install MongoDB Community Edition procedure:
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]
Run the following commands in a terminal or shell to fully remove the
Ubuntu mongodb package before retrying the installation
procedure:
sudo apt remove mongodb sudo apt purge mongodb sudo apt autoremove
Note
sudo apt purge mongodb removes any default configuration files
installed by the Ubuntu mongodb package. If you have
modified these configuration files and want to keep those
modifications, copy the files to another directory such as
/home/your-user-name.
If your output includes a mix of mongodb-org and
mongodb binaries, you may need to first apt remove, apt
purge, and apt autoremove the mongodb-org package
before attempting to remove and purge the Ubuntu mongodb
package. After clearing all MongoDB-related packages, retry the
installation procedure.
mongod reports errors related to opening a socket
You may encounter the Socket is already in use or
Failed to unlink socket file errors when starting a
mongod. These errors generally indicate
another process using the configured port for the
mongod process, typically another
mongod running on the system.
The following example uses the ss utility to list all open
TCP (-t) or 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
The following partial output shows a mongod process
listening on the 27017 port. Attempting to run another mongod
process on that same port will result in socket errors.
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))
If the system has a mongod or other system
process running on your desired port, you must either shut the
existing process down or select a new port for the new
mongod process. You can specify the
net.port configuration file
option to change the port that the mongod
listens on.
mongod reports errors related to the data directory
Users may encounter errors that resemble the following in the
mongod
process log:
Data directory ... not found Attempted to create lock file on a read-only directory: ...
Generally, these errors indicate that the MongoDB data directory
either doesn't exist, or isn't accessible to the
mongod.
The data directory must exist
The data directory is specified with the storage.dbPath
setting in the configuration file, or
with the --dbpath option to
mongod on the command line.
If you installed MongoDB through the
aptpackage manager, the default/etc/mongod.confconfiguration file setsstorage.dbPathto/var/lib/mongodb.If you are running
mongodon the command line, and omitting the--dbpathoption entirely, MongoDB uses a default--dbpathof/data/db.
Whether you are using one of the data directory paths above, or
providing your own path in the configuration file or on the command
line, make sure that the data directory exists on your filesystem
prior to starting the mongod. You can create
directories on Ubuntu with the mkdir command.
The data directory must be accessible
The data directory must be configured with the appropriate
permissions and ownership settings to allow the
mongod to read, write, and
navigate the directory contents (rwx user or group permissions).
Use chown, and chmod to modify permissions and set
user:group ownership as appropriate prior to starting the
mongod.
Starting mongod using the data directory
Users starting the mongod as a service (e.g. using either sudo
systemctl start mongod or sudo service mongod start) typically
only see these errors if they modified the default
dbPath value in the /etc/mongod.conf to:
A directory that does not allow the
mongodbuser ormongodbgroup to read, write, or execute (rwx) the directory and its contents, orA directory that does not exist.
Users starting the mongod without using the
service definition (e.g. using the terminal to launch mongod)
typically see these errors if: