quarkusio/quarkus · error · RuntimeException

Failed to create URL for cached resource

Error message

Failed to create URL for cached resource: ${name}

What it means

AotRunnerClassLoader serves cached resources via synthetic 'cached:' URLs handled by CachedResourceURLStreamHandler. createCachedResourceURL wraps MalformedURLException in a RuntimeException; since the protocol string is a constant, this only fails if the URL cannot be constructed with the custom stream handler. The resulting error names the resource whose URL could not be created.

Solutions

1. Rebuild the AOT package (mvn clean package) to regenerate a valid quarkus-application.dat cache.
2. Check the named resource entry in the cache for corruption or invalid characters.
3. Report/inspect if a java.net.URLStreamHandlerFactory installed elsewhere blocks the cached: protocol.

try (InputStream in = cl.getResourceAsStream(name)) {
    // use resource
} catch (RuntimeException e) {
    if (e.getMessage() != null && e.getMessage().startsWith("Failed to create URL for cached resource")) {
        throw new IllegalStateException("AOT cache corrupted; rebuild package", e);
    } throw e;
}

When it happens

Trigger: getResource/findResource/getResources/findResources calling createCachedResourceURL when new URL(null, "cached:"+name, handler) throws MalformedURLException — practically only when the resource name makes the URL malformed or the 'cached:' protocol handler cannot be registered.

Common situations: Corrupted or unusual resource names coming from a damaged quarkus-application.dat cache, or JVM restrictions on custom URL stream handler factories.

Related errors

• class reading failed
• class reading failed
• Expected : after attribute
• Failed to build AOT enhanced container image:
• Failed to convert REST client URL to URI

AI-assisted analysis of quarkusio/quarkus@e1c734241f (2026-09-05). Data as JSON: /api/errors/20d338bba75181db. Report an issue: GitHub.

Appendix: source

Thrown at independent-projects/bootstrap/runner/src/main/java/io/quarkus/bootstrap/runner/AotRunnerClassLoader.java:215

        // For cached resources, return the stream directly without URL/URLConnection overhead
        final byte[] data = serviceFiles.get(name);
        if (data != null) {
            return new ByteArrayInputStream(data);
        }

        if (isKnownAbsentResource(name)) {
            return null;
        }

        return getParent().getResourceAsStream(name);
    }

    private URL createCachedResourceURL(String name, byte[] data) {
        try {
            return new URL(null, "cached:".concat(name), new CachedResourceURLStreamHandler(data));
        } catch (MalformedURLException e) {
            throw new RuntimeException("Failed to create URL for cached resource: " + name, e);
        }
    }

    /**
     * URL stream handler for cached resources.
     */
    private static class CachedResourceURLStreamHandler extends URLStreamHandler {
        private final byte[] data;

        CachedResourceURLStreamHandler(byte[] data) {
            this.data = data;
        }

        @Override
        protected URLConnection openConnection(URL url) {
            return new CachedResourceURLConnection(url, data);
        }
    }

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