standard_init_linux.go: exec user process caused: no such file or directory

Docker exec format error is architecturally caused — a container binary compiled for arm64 runs on amd64 hardware or vice versa, and the OS kernel refuses to execute it. This error comes from the Linux kernel before any Docker-specific code runs, which is why the message is terse. This error became common with Docker BuildKit multi-platform capabilities. Running docker buildx build --platform linux/arm64 . on an amd64 CI runner builds an arm64 image correctly, but if that image is accidentally pushed without specifying platform and then pulled on an amd64 server, exec format error appears at container startup — not during the build. The docker inspect image-name command shows the compiled architecture of any local image under the Architecture field. For images pulled from a registry with multi-arch manifests, docker manifest inspect image-name lists all available platform variants and which one Docker pulled for your current host. Go binaries and statically compiled Rust/C applications are the most portable: they can be cross-compiled to produce arm64 binaries on amd64 machines without QEMU emulation. Python and Node.js containers are interpreted and architecture-independent at the application layer, but their base images (the Python or Node.js interpreter itself) must match the target architecture. Alpine-based images (node:18-alpine, python:3.11-alpine) are available for both amd64 and arm64 as multi-arch manifests automatically.