apache/flink · error · FileAlreadyExistsException

File already exists: {}

Error message

File already exists: {}

What it means

Thrown as FileAlreadyExistsException by LocalFileSystem.create() when the target filePath already exists AND WriteMode.NO_OVERWRITE is set. It guards against silently clobbering existing data on create.

Source

Thrown at flink-core/src/main/java/org/apache/flink/core/fs/local/LocalFileSystem.java:256

            // Important: The 'exists()' check above must come before the 'isDirectory()' check to
            //            be safe when multiple parallel instances try to create the directory

            // exists and is not a directory -> is a regular file
            throw new FileAlreadyExistsException(file.getAbsolutePath());
        } else {
            File parent = file.getParentFile();
            return (parent == null || mkdirsInternal(parent))
                    && (file.mkdir() || file.isDirectory());
        }
    }

    @Override
    public FSDataOutputStream create(final Path filePath, final WriteMode overwrite)
            throws IOException {
        checkNotNull(filePath, "filePath");

        if (exists(filePath) && overwrite == WriteMode.NO_OVERWRITE) {
            throw new FileAlreadyExistsException("File already exists: " + filePath);
        }

        final Path parent = filePath.getParent();
        if (parent != null && !mkdirs(parent)) {
            throw new IOException("Mkdirs failed to create " + parent);
        }

        final File file = pathToFile(filePath);
        return new LocalDataOutputStream(file);
    }

    @Override
    public boolean rename(final Path src, final Path dst) throws IOException {
        final File srcFile = pathToFile(src);
        final File dstFile = pathToFile(dst);

        final File dstParent = dstFile.getParentFile();

View on GitHub (pinned to 2f3c205e92)

Solutions

1. Delete the existing target before creating: `fs.delete(path, true)` then create.
2. Use WriteMode.OVERWRITE if clobbering is acceptable: `fs.create(path, WriteMode.OVERWRITE)`.
3. Use a unique output path per run (timestamp/uuid suffix).
4. Add a startup cleanup step in the job.

Example fix

// before
fs.create(path, WriteMode.NO_OVERWRITE);

// after
if (fs.exists(path)) fs.delete(path, true);
fs.create(path, WriteMode.NO_OVERWRITE);

FSDataOutputStream safeCreate(FileSystem fs, Path p, WriteMode mode) throws IOException {
    if (mode == WriteMode.NO_OVERWRITE && fs.exists(p))
        throw new FileAlreadyExistsException("will not overwrite: " + p);
    return fs.create(p, mode);
}

try {
    fs.create(p, WriteMode.NO_OVERWRITE);
} catch (FileAlreadyExistsException e) {
    fs.delete(p, true);
    fs.create(p, WriteMode.NO_OVERWRITE);
}

When it happens

Trigger: Calling create(path, WriteMode.NO_OVERWRITE) on a path where exists(path) is true.

Common situations: Output file/dir from a previous run still present; re-running a job without clearing output; sink configured for no-overwrite but target not cleaned.

Related errors

• File {} does not exist or the user running Flink ('{}') has
• Directory {} is not empty
• {}
• Mkdirs failed to create {}
• Could not create writer state serializer.

AI-assisted analysis of apache/flink@2f3c205e92 (2026-08-14). Data as JSON: /api/errors/ed29e94b4f839c59. Report an issue: GitHub.