What causes "Output directory NOT sucessfully created to: " in java-native-access/jna?

Verify the parent directory of comRootDir exists and is writable before running TlbImp

java-native-access/jna · error · java.io.FileNotFoundException

Output directory NOT sucessfully created to: <comRootDir>

Error message

Output directory NOT sucessfully created to: <comRootDir>

What it means

TlbImp's createDir deletes any existing comRootDir and then calls mkdirs(); if directory creation fails (permissions, path in use, disk issues) it throws this FileNotFoundException. It means the type-library-to-Java generator could not prepare its output directory. Note the message text says 'to' but means the output path.

Source

Thrown at contrib/platform/src/com/sun/jna/platform/win32/COM/tlb/TlbImp.java:156

    private void createDir() throws FileNotFoundException {
        String _outputDir = this.cmdlineArgs.getParam(CMD_ARG_OUTPUT_DIR);
        String path = "_jnaCOM_" + System.currentTimeMillis() + "\\myPackage\\"
                + this.typeLibUtil.getName().toLowerCase() + "\\";

        if (_outputDir != null) {
            this.comRootDir = new File(_outputDir + "\\" + path);
        } else {
            String tmp = System.getProperty("java.io.tmpdir");
            this.comRootDir = new File(tmp + "\\" + path);
        }

        if (this.comRootDir.exists())
            this.comRootDir.delete();

        if (this.comRootDir.mkdirs()) {
            logInfo("Output directory sucessfully created.");
        } else {
            throw new FileNotFoundException(
                    "Output directory NOT sucessfully created to: "
                            + this.comRootDir.toString());
        }
    }

    private String getPackageName() {
        return "myPackage." + this.typeLibUtil.getName().toLowerCase();
    }

    private void writeTextFile(String filename, String str) throws IOException {
        String file = this.comRootDir + File.separator + filename;
        BufferedOutputStream bos = new BufferedOutputStream(
                new FileOutputStream(file));
        bos.write(str.getBytes());
        bos.close();
    }

    private void writeTlbClass(TlbBase tlbBase) throws IOException {

View on GitHub (pinned to d036ad9781)

Solutions

Verify the parent directory of comRootDir exists and is writable before running TlbImp
Close any processes locking the output directory and delete it manually, then re-run
Run the generator with sufficient privileges or choose an output path under a user-writable location
Check the full path string in the message for typos or invalid characters

Example fix

// before
TlbImp imp = new TlbImp("C:\\Program Files\\MyLib\\my.tlb", "C:\\Program Files\\out");
// after
File out = new File("C:\\dev\\generated");
out.mkdirs(); // ensure parent exists and is writable first
if (!out.isDirectory()) throw new IllegalStateException("output dir not usable: " + out);
TlbImp imp = new TlbImp("C:\\dev\\libs\\my.tlb", out.getAbsolutePath());

Defensive patterns

Strategy: validation

Validate before calling

File dir = new File(outPath);
if (dir.exists() && !dir.delete()) throw new IllegalStateException("cannot delete old dir " + dir);
if (!dir.mkdirs() && !dir.isDirectory()) throw new IllegalStateException("cannot create " + dir);

Try / catch

try { imp.startCOM2Java(); } catch (FileNotFoundException e) { log.error("output dir unusable: " + e.getMessage()); }

Prevention

Check parent directory writability before invoking TlbImp
Avoid output paths other processes may lock
Use user-writable paths, not Program Files

When it happens

Trigger: Calling com2java / TlbImp.startCOM2Java when comRootDir cannot be created: parent directory missing or unwritable, an undeletable file occupies the path, or the path is a locked/removable location.

Common situations: Running the JNA COM code generator with an output directory under a read-only or non-existent parent; insufficient Windows permissions on the target folder; another process (IDE, explorer) holding a handle on the directory so delete() fails and mkdirs() then fails too.

Understand the failure class

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

Related errors

AI-assisted analysis of java-native-access/jna@d036ad9781 (2026-09-12). Data as JSON: /api/errors/b85516c9a220f1c2. Report an issue: GitHub.