Docker is fantastic right up until it throws one of its greasy, context-free error messages at you and you lose twenty minutes to a thing that has a one-line fix. I've been collecting these — the exact strings, and the first thing to check for each. Here are the ten that eat the most time.
1. Cannot connect to the Docker daemon at unix:///var/run/docker.sock
The engine isn't reachable. In order of likelihood: the daemon isn't running (systemctl status docker), you're not in the docker group (sudo usermod -aG docker $USER, then log out and back in), or you're pointing at the wrong DOCKER_HOST. It's almost never Docker being broken — it's Docker not being up or you not being allowed.
3. Bind for 0.0.0.0:8080 failed: port is already allocated
Something already owns that port — often a container you forgot was running. docker ps to find it, or ss -tlnp | grep 8080 for a non-Docker process. Stop the holder or map to a different host port.
5. exec format error
You built the image for one CPU architecture and ran it on another — the classic Apple Silicon (arm64) build landing on an amd64 server. Build multi-arch with docker buildx, or pin --platform to match your target.
6. OCI runtime create failed
A low-level container-start failure. The useful part is always after the colon — a missing binary, a bad mount, a permissions problem. Read the full message; OCI runtime create failed itself tells you nothing.
8. TLS handshake timeout
Usually not a cert problem — it's a network path issue (a proxy, MTU, or firewall) between you and the registry, masquerading as TLS. Test raw connectivity before you touch certificates.
— the top errors, launcher, and runbooks in one place
Which Docker error has personally cost you the most hours? Genuinely curious which of these tops the list for other people.
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