apache/shardingsphere · error · FileIOException

30020

30020

Error message

File access failed, file is: %s

What it means

FileIOException (error code 30020) thrown by ExportUtils.exportToFile when writing exported data to the given path fails: parent directories are created if missing, then the bytes are written via Files.newOutputStream; any IOException (permission denied, non-directory parent, disk full) is caught and converted to FileIOException naming the file.

Source

Thrown at proxy/backend/core/src/main/java/org/apache/shardingsphere/proxy/backend/util/ExportUtils.java:53

    
    /**
     * Export configuration data to specified file.
     *
     * @param filePath file path
     * @param exportedData exported configuration data
     * @throws FileIOException file IO exception
     */
    @SuppressWarnings("ResultOfMethodCallIgnored")
    public static void exportToFile(final String filePath, final String exportedData) {
        File file = new File(filePath);
        if (!file.exists() && null != file.getParentFile()) {
            file.getParentFile().mkdirs();
        }
        try (OutputStream output = Files.newOutputStream(Paths.get(file.toURI()))) {
            output.write(exportedData.getBytes());
            output.flush();
        } catch (final IOException ignore) {
            throw new FileIOException(file);
        }
    }
}

View on GitHub (pinned to e952770a21)

Solutions

1. Choose an export directory that exists and is writable by the proxy process (pre-create it and chown/chmod appropriately)
2. In containers, export to a mounted writable volume, not the image root
3. Check disk space on the proxy host and retry after freeing space

Example fix

-- before
EXPORT DATABASE CONFIGURATION TO '/etc/shardingsphere/export.yaml';

-- after
EXPORT DATABASE CONFIGURATION TO '/opt/shardingsphere/export/export.yaml';

File dir = targetFile.getParentFile();
if (dir == null || (!dir.exists() && !dir.mkdirs()) || !dir.canWrite()) {
    throw new IllegalArgumentException("Export directory not writable: " + dir);
}
if (targetFile.exists() && targetFile.isDirectory()) {
    throw new IllegalArgumentException("Export target is a directory: " + targetFile);
}

try {
    ExportUtils.exportToFile(path, data);
} catch (final FileIOException ex) {
    // surface the path; switch to a writable directory and retry
}

When it happens

Trigger: EXPORT operations (e.g. EXPORT DATABASE CONFIGURATION / metadata export) targeting a path where mkdirs() failed or the open/write fails: unwritable directory, path is an existing directory, read-only filesystem, or no space left.

Common situations: Exporting to /tmp or a config dir not writable by the proxy user; running the proxy in a container with a read-only root filesystem; passing a path whose parent exists as a regular file; disk exhaustion on the proxy host.

Related errors

• 0
• 30001
• 30020
• 30020
• 30020

AI-assisted analysis of apache/shardingsphere@e952770a21 (2026-08-14). Data as JSON: /api/errors/254f4c742c2eeb8e. Report an issue: GitHub.