quarkusio/quarkus · error · UncheckedIOException

java.io.UncheckedIOException

Error message

java.io.UncheckedIOException

What it means

PathTreeClassPathElement.apply opens the original PathTree to run a function and wraps any IOException in java.io.UncheckedIOException so it can be thrown from a lambda/supplier context. It signals that reading the backing filesystem tree failed while the element was being accessed. The message carries the wrapped IOException cause.

Solutions

1. Check the cause IOException for the real problem (missing file vs permission)
2. Ensure the application jars are not deleted/moved while running
3. Restore the missing classpath resource or rebuild the application
4. Retry on transient filesystem errors

Example fix

// before
byte[] data = element.getData(); // UncheckedIOException
// after
try {
    byte[] data = element.getData();
} catch (UncheckedIOException e) {
    LOGGER.error("Classpath element unreadable", e.getCause());
}

if (!Files.exists(pathTreeRoot)) throw new IllegalStateException("classpath element missing: " + pathTreeRoot);

try {
    byte[] data = element.getData();
} catch (UncheckedIOException e) {
    IOException cause = e.getCause();
    // log and fall back or abort startup
}

When it happens

Trigger: Calling methods on a PathTreeClassPathElement (via apply) after the underlying zip/file was deleted or moved, or when opening the PathTree throws IOException (I/O error reading the jar/file).

Common situations: Running application with jars removed while running (hot redeploys, cleanup scripts deleting target/), filesystem errors, or files locked on Windows.

Related errors

• An error occurred while processing
• Cannot create directory
• Could not create directory
• Could not create directory
• Could not create directory

AI-assisted analysis of quarkusio/quarkus@e1c734241f (2026-09-05). Data as JSON: /api/errors/774ce2e235fd60fc. Report an issue: GitHub.

Appendix: source

Thrown at independent-projects/bootstrap/core/src/main/java/io/quarkus/bootstrap/classloading/PathTreeClassPathElement.java:143

            });
            return ret;
        });
    }

    @Override
    public <T> T apply(Function<OpenPathTree, T> func) {
        lock.readLock().lock();
        try {
            if (pathTree.isOpen()) {
                return func.apply(pathTree);
            }
            //we still need this to work if it is closed, so shutdown hooks work
            //once it is closed it simply does not hold on to any resources
            final boolean interrupted = Thread.interrupted();
            try (OpenPathTree openTree = pathTree.getOriginalTree().open()) {
                return func.apply(openTree);
            } catch (IOException e) {
                throw new UncheckedIOException(e);
            } finally {
                if (interrupted) {
                    Thread.currentThread().interrupt();
                }
            }
        } finally {
            lock.readLock().unlock();
        }
    }

    @Override
    public Set<String> getProvidedResources() {
        return pathTree.getResourceNames();
    }

    @Override
    public boolean containsReloadableResources() {
        return !pathTree.isArchiveOrigin();

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