facebook/flow · error

mkdirp: mkdir {} failed: {}

Error message

mkdirp: mkdir {} failed: {}

What it means

mkdirp creates a path one component at a time (unix branch, with explicit mode from _perm). AlreadyExists is tolerated, but any other error panics with the failing component. Real causes: EACCES/EROFS on a parent, ENOTDIR when a regular file occupies a component position, ENAMETOOLONG, or EDQUOT.

Source

Thrown at rust_port/crates/flow_common/src/files.rs:1360

        [first_part, rest @ ..]
            if format!("{}{}", first_part, std::path::MAIN_SEPARATOR) == path_prefix =>
        {
            rest
        }
        _ => &parts,
    };
    parts.iter().fold(path_prefix, |path_str, part| {
        let new_path_str = Path::new(&path_str)
            .join(part)
            .to_string_lossy()
            .into_owned();
        #[cfg(unix)]
        {
            use std::os::unix::fs::DirBuilderExt;
            match std::fs::DirBuilder::new().mode(_perm).create(&new_path_str) {
                Ok(()) => {}
                Err(e) if e.kind() == std::io::ErrorKind::AlreadyExists => {}
                Err(e) => panic!("mkdirp: mkdir {} failed: {}", new_path_str, e),
            }
        }
        #[cfg(not(unix))]
        {
            match std::fs::create_dir(&new_path_str) {
                Ok(()) => {}
                Err(e) if e.kind() == std::io::ErrorKind::AlreadyExists => {}
                Err(e) => panic!("mkdirp: mkdir {} failed: {}", new_path_str, e),
            }
        }
        new_path_str
    });
}

pub fn generate_is_within_node_modules_fn(
    root: &Path,
    options: &FileOptions,
) -> impl Fn(&str) -> bool {

View on GitHub (pinned to f88ac94bcf)

Solutions

1. Remove or rename the file occupying the failing component path shown in the panic
2. Fix write permissions on the parent directory (chmod/chown)
3. Set TMPDIR to a clean, writable, local directory and retry
4. Shorten deep paths or enable long-path support on Windows

Example fix

# before
# a stray FILE named 'flow' blocks <tmp>/flow/...
touch /tmp/flow && flow check   # panics: mkdirp: mkdir /tmp/flow/x failed: Not a directory

# after
rm /tmp/flow
flow check

# verify every ancestor of flow's temp/cache path is a directory and writable
path="$TMPDIR/flow"; p=""
for part in $(echo "$path" | tr '/' ' '); do
  p="$p/$part"
  [ -e "$p" ] && [ ! -d "$p" ] && echo "BLOCKED: $p is a file"
done
test -w "$(dirname "$path")" || echo "parent not writable"

When it happens

Trigger: Creating flow's cache/temp directory trees when an intermediate component is a regular file (path like <tmp>/file.json/sub); parent directory lacks write permission; read-only or quota-limited filesystem; extremely long paths.

Common situations: TMPDIR pointing at a full/locked-down location; a previous crash leaving a file where flow expects a directory tree; sandboxed environments denying mkdir; shared caches on network volumes.

Related errors

• fd_of_path: mkdir_no_fail({:?}): {}
• fd_of_path: open({:?}): {}
• mkdir_no_fail({:?}): {}
• failed to create {}: {}
• Failed to open log file '{}': {}

AI-assisted analysis of facebook/flow@f88ac94bcf (2026-08-20). Data as JSON: /api/errors/d79fad761904ebe1. Report an issue: GitHub.