MyCATApache/Mycat-Server · error · java.io.IOException

Mkdirs failed to create

Error message

Mkdirs failed to create {parentDir}

What it means

JarLoader.unJar extracts a jar's entries into a target directory; before writing each file it creates parent directories with File.mkdirs(). If mkdirs() returns false and the path is still not an existing directory, it throws IOException('Mkdirs failed to create <parentDir>').

Solutions

1. Ensure the extraction (toDir) directory exists and is writable by the Mycat process user
2. Remove any regular file that occupies the same path as a needed parent directory
3. Check filesystem permissions/SELinux and disk space; verify path length limits are not exceeded
4. Extract to a different writable directory

Example fix

// before
dir.mkdirs(); // silently fails on read-only fs
// after
if (!dir.exists() && !dir.mkdirs()) {
    throw new IOException("Cannot create dir: " + dir);
}

File toDir = new File(target);
if (!toDir.canWrite()) throw new IllegalStateException("No write access: " + toDir);

try {
    loader.loadJar(path);
} catch (IOException e) {
    if (e.getMessage().startsWith("Mkdirs failed")) {
        // check permissions/ownership on extraction dir, then retry
    }
}

When it happens

Trigger: Extracting a jar (via loadJar) into a directory where parent folders cannot be created: no write permission on toDir, a file exists where a directory is needed, path too long, or read-only filesystem.

Common situations: Loading a user-defined jar from a read-only classpath directory; running Mycat as a user without write access to the extraction directory; SELinux/AppArmor restrictions; a stale file occupying the target path.

Understand the failure class

Background: mkdir permission denied (EACCES): failed to create directory errors explained — this error's family across 32 libraries.

Related errors

• Error opening jar
• Failed to create local dir in $newDir.
• Failed to delete:
• Failed to list files for dir:
• Failed to create a temp directory

AI-assisted analysis of MyCATApache/Mycat-Server@65f8d8beb7 (2026-09-11). Data as JSON: /api/errors/95fc82f2772353fa. Report an issue: GitHub.

Appendix: source

Thrown at src/main/java/io/mycat/config/classloader/JarLoader.java:25

import java.net.URLClassLoader;
import java.io.*;
import java.util.*;

public class JarLoader {
	  /** Unpack a jar file into a directory. */
	  public static void unJar(File jarFile, File toDir) throws IOException {
	    JarFile jar = new JarFile(jarFile);
	    try {
	      Enumeration entries = jar.entries();
	      while (entries.hasMoreElements()) {
	        JarEntry entry = (JarEntry)entries.nextElement();
	        if (!entry.isDirectory()) {
	          InputStream in = jar.getInputStream(entry);
	          try {
	            File file = new File(toDir, entry.getName());
	            if (!file.getParentFile().mkdirs() && !file.getParentFile().isDirectory()) {

	                throw new IOException("Mkdirs failed to create " + 
	                                      file.getParentFile().toString());

	            }
	            OutputStream out = new FileOutputStream(file);
	            try {
	              byte[] buffer = new byte[8192];
	              int i;
	              while ((i = in.read(buffer)) != -1) {
	                out.write(buffer, 0, i);
	              }
	            } finally {
	              out.close();
	            }
	          } finally {
	            in.close();
	          }
	        }
	      }

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