quarkusio/quarkus · error · IOException

Failed to create an instance of java.nio.file.Path from <url

Error message

Failed to create an instance of java.nio.file.Path from <urlSpec>

What it means

urlSpecToPath converts a URL external form (e.g. file:/path or jar:file:...!/entry) to a java.nio.file.Path via Paths.get(URL.toURI()). If the URL/URI is malformed or the scheme has no filesystem provider, it throws IOException 'Failed to create an instance of java.nio.file.Path from <urlSpec>'.

Source

Thrown at independent-projects/tools/devtools-common/src/main/java/io/quarkus/maven/utilities/MojoUtils.java:342

    public static Path getResourceOrigin(ClassLoader cl, final String name) throws IOException {
        URL url = cl.getResource(name);
        if (url == null) {
            throw new IOException("Failed to locate the origin of " + name);
        }
        String classLocation = url.toExternalForm();
        if (url.getProtocol().equals("jar")) {
            classLocation = classLocation.substring(4, classLocation.length() - name.length() - 2);
        } else {
            classLocation = classLocation.substring(0, classLocation.length() - name.length());
        }
        return urlSpecToPath(classLocation);
    }

    private static Path urlSpecToPath(String urlSpec) throws IOException {
        try {
            return Paths.get(new URL(urlSpec).toURI());
        } catch (Throwable e) {
            throw new IOException(
                    "Failed to create an instance of " + Path.class.getName() + " from " + urlSpec, e);
        }
    }
}

View on GitHub (pinned to e1c734241f)

Solutions

1. URI-encode the URL spec (replace spaces with %20) before conversion
2. Handle jar URLs specially: extract the jar file path before the '!/' separator and resolve the entry manually
3. For non-file schemes, fetch the resource content instead of expecting a filesystem Path
4. Check that the resource origin is a real file or jar on disk

Example fix

// before
Path p = Paths.get(new URL("file:/dir with space/x.jar").toURI()); // may fail upstream
// after
String spec = "file:/dir with space/x.jar".replace(" ", "%20");
Path p = Paths.get(new URI(spec));

static boolean isFileUrl(String urlSpec) {
    try {
        URI u = new URI(urlSpec);
        return "file".equals(u.getScheme()) || "jar".equals(u.getScheme());
    } catch (URISyntaxException e) {
        return false;
    }
}

try {
    Path p = MojoUtils.getResourceOrigin(cl, name);
} catch (IOException e) {
    log.warn("Cannot map {} to filesystem path (nested jar or remote URL?): {}", name, e.getMessage());
}

When it happens

Trigger: Called from getResourceOrigin when the resource URL cannot be converted to a URI/Path — e.g. jar URLs with nested '!/' entries (JAR-inside-JAR), URLs with spaces or illegal characters not encoded, or non-file schemes (http:, jrt:) without a provider.

Common situations: Spring Boot fat-jar style nested jars, unencoded spaces in paths (macOS 'Application Support'), resources served over http in exotic classloaders, running under GraalVM native image where jar protocol handling differs.

Related errors

• There were a problem while reading the resource dir '<name>'
• Failed to read %s
• Failed to read resources from classpath
• Could not read class path resources having path '${resourceP
• Failed to load + pomPropsPath + from the classpath

AI-assisted analysis of quarkusio/quarkus@e1c734241f (2026-09-05). Data as JSON: /api/errors/38c3750d4c8850bc. Report an issue: GitHub.