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

Failed to create temporary file for name library: e.getMessa

Error message

Failed to create temporary file for name library: e.getMessage()

What it means

While unpacking the native library resource to a temporary file, any IOException encountered (creating the temp file or writing the buffered stream) is wrapped as IOException 'Failed to create temporary file for <name> library: <reason>'. The native library could not be materialized on disk, so loading cannot proceed.

Source

Thrown at src/com/sun/jna/Native.java:1252

            try {
                // Suffix is required on windows, or library fails to load
                // Let Java pick the suffix, except on windows, to avoid
                // problems with Web Start.
                File dir = getTempDir();
                lib = File.createTempFile(JNA_TMPLIB_PREFIX, Platform.isWindows()?".dll":null, dir);
                if (!Boolean.getBoolean("jnidispatch.preserve")) {
                    lib.deleteOnExit();
                }
                LOG.log(DEBUG, "Extracting library to {0}", lib.getAbsolutePath());
                fos = new FileOutputStream(lib);
                int count;
                byte[] buf = new byte[1024];
                while ((count = is.read(buf, 0, buf.length)) > 0) {
                    fos.write(buf, 0, count);
                }
            }
            catch(IOException e) {
                throw new IOException("Failed to create temporary file for " + name + " library: " + e.getMessage());
            }
            finally {
                try { is.close(); } catch(IOException e) { }
                if (fos != null) {
                    try { fos.close(); } catch(IOException e) { }
                }
            }
        }
        return lib;
    }

    /**
     * Initialize field and method IDs for native methods of this class.
     * Returns the size of a native pointer.
     **/
    private static native int sizeof(int type);

    private static native String getNativeVersion();

View on GitHub (pinned to d036ad9781)

Solutions

1. Set -Djna.tmpdir (or java.io.tmpdir) to a writable, executable directory and retry
2. Free disk space / raise quota on the temp filesystem
3. If the library is already unpacked on disk, set -Djna.nounpack=true and point jna.boot.library.path at it
4. Check the embedded reason in the message (permission vs space) and fix filesystem permissions accordingly

Example fix

// before
java -jar app.jar  # tmpdir read-only
// after
java -Djna.tmpdir=/var/lib/app/tmp -jar app.toml -> ensure /var/lib/app/tmp is writable and mounted with exec

// ensure temp dir is writable before first JNA call
File tmp = new File(System.getProperty("jna.tmpdir", System.getProperty("java.io.tmpdir")));
if (!tmp.canWrite()) throw new IllegalStateException("JNA temp dir not writable: " + tmp);
if (tmp.getUsableSpace() < 10L * 1024 * 1024) throw new IllegalStateException("Low space in JNA temp dir: " + tmp);

try { Native.load("c", CLibrary.class); } catch (UnsatisfiedLinkError e) { Throwable c = e; while ((c = c.getCause()) != null) { if (c instanceof IOException && String.valueOf(c.getMessage()).contains("Failed to create temporary file")) { throw new IllegalStateException("Fix jna.tmpdir permissions/space", e); } } throw e; }

When it happens

Trigger: extractFromResourcePath stream-copy loop failing because the temp directory is read-only, full, or File.createTempFile failed; disk quota exceeded; antivirus/permissions blocking file creation in java.io.tmpdir.

Common situations: Containers with read-only /tmp; tmpwatch cleaner races; small tmpfs; corporate policy denying execute from temp; running as a user without write access to the temp dir.

Understand the failure class

Background: "failed to write file", "Could not save figure", "Error saving remote file" — file write failed: causes and fixes across languages and libraries — this error's family across 38 libraries.

Related errors

• Can't obtain InputStream for resourcePath
• No trash location found (define fileutils.trash to be the pa
• UnsatisfiedLinkError(e.getMessage())
• Native library (resourcePath) not found in resource path (pa
• File URL url could not be properly decoded

AI-assisted analysis of java-native-access/jna@d036ad9781 (2026-09-12). Data as JSON: /api/errors/473215a92424d5c6. Report an issue: GitHub.