gleam-lang/gleam · error

invalid folder

Error message

invalid folder

What it means

In get_foldername, when the project root path is ".", env::current_dir() is unwrapped with .expect("invalid folder"). If the current directory cannot be read (deleted, no permission) the process panics; if the directory has no valid file_name or is not UTF-8-representable, it returns UnableToFindProjectRoot instead.

Solutions

1. cd into an existing, readable directory before running the command
2. Recreate the deleted directory or restart the shell
3. Check permissions on the current directory
4. Pass an explicit project path instead of `.` (e.g. `gleam new my_app`)

Example fix

// before (cwd deleted)
$ cd /tmp/gone && gleam new .
// after
$ cd /tmp && gleam new my_app

// check cwd before `gleam new .`
match std::env::current_dir() {
    Ok(d) => println!("cwd ok: {}", d.display()),
    Err(e) => eprintln!("fix cwd first: {}", e),
}

When it happens

Trigger: Running `gleam new .` (get_valid_project_name -> get_foldername) from a working directory that no longer exists or is inaccessible to the process.

Common situations: Starting gleam from a directory removed by another process/terminal; ephemeral CI containers with vanished cwd; directories with permission changes mid-session; using a cwd path outside the UTF-8 domain on some platforms.

Related errors

• Failed to get current directory
• Directory name
• Final result error writing
• Index out of bounds
• is_gleam_path(): strip_prefix

AI-assisted analysis of gleam-lang/gleam@15b07c7830 (2026-09-14). Data as JSON: /api/errors/9f4642a909b86d91. Report an issue: GitHub.

Appendix: source

Thrown at compiler-cli/src/new.rs:491

                decided: suggested_name,
            },
            None => ProjectName::Derived {
                folder: initial_name,
                decided: suggested_name,
            },
        });
    }

    Err(Error::InvalidProjectName {
        name: initial_name,
        reason: invalid_reason,
    })
}

fn get_foldername(path: &str) -> Result<String, Error> {
    match path {
        "." => env::current_dir()
            .expect("invalid folder")
            .file_name()
            .and_then(|x| x.to_str())
            .map(ToString::to_string)
            .ok_or(Error::UnableToFindProjectRoot {
                path: path.to_string(),
            }),
        _ => Utf8Path::new(path)
            .file_name()
            .map(ToString::to_string)
            .ok_or(Error::UnableToFindProjectRoot {
                path: path.to_string(),
            }),
    }
}

#[derive(Debug, Clone)]
enum ProjectName {
    Provided { decided: String },

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