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#ubuntu
apt "dpkg was interrupted, you must manually run dpkg --configure -a": finish what was started
Fix apt "E: dpkg was interrupted, you must manually run sudo dpkg --configure -a": run it, then fix what stops it: a full disk, broken packages or a failing script.
Beginner · 3 min read
apt "GPG error: NO_PUBKEY": add the key the right way, without apt-key
Fix apt "GPG error: The following signatures couldn't be verified: NO_PUBKEY": add the vendor's key to /etc/apt/keyrings with signed-by, and why apt-key is gone.
Intermediate · 4 min read
apt "E: Unable to locate package": update, enable the component, or find its real name
Fix apt "E: Unable to locate package": run apt update, enable universe or contrib, find the right package name, add the vendor's repository, and handle Docker images.
Beginner · 4 min read
PostgreSQL "Peer authentication failed for user": connect the right way, or change pg_hba.conf
Fix PostgreSQL "Peer authentication failed for user": use sudo -u postgres, connect over TCP with -h localhost, or change pg_hba.conf to scram-sha-256 and reload.
Beginner · 4 min read
Apache "AH00558: Could not reliably determine the server's fully qualified domain name": what it means, and the fix
Fix Apache AH00558: it's only a warning, set ServerName globally on Ubuntu or RHEL. If your site is still down, the real error is elsewhere, and here is how to find it.
Beginner · 3 min read
WSL "WslRegisterDistribution failed with error: 0x80370102": turn on virtualization
Fix WSL "WslRegisterDistribution failed with error: 0x80370102": enable virtualization in the firmware, Virtual Machine Platform, the hypervisor or nested virtualization.
Beginner · 3 min read
"E: Could not get lock /var/lib/dpkg/lock-frontend": what is holding apt, and what to do
Fix "Could not get lock /var/lib/dpkg/lock-frontend" on Ubuntu and Debian: find the process holding it, wait safely, and repair an interrupted dpkg.
Beginner · 3 min read
pip "error: externally-managed-environment": install Python packages the right way
Fix pip "externally-managed-environment" on Ubuntu 24.04 and Debian 12: use apt, a virtual environment or pipx, and know when --break-system-packages is acceptable.
Beginner · 3 min read
"sudo: unable to resolve host": fix /etc/hosts after a hostname change
Fix "sudo: unable to resolve host … Name or service not known" on Ubuntu and Debian: add the hostname to /etc/hosts, and keep cloud-init from undoing it.
Beginner · 3 min read