elastic/elasticsearch · error · InvalidUserDataException

Failed to build classpath URLs.

Error message

Failed to build classpath URLs.

What it means

Thrown while building a URL[] from a FileCollection for the fixtures classloader: one of the files produced a MalformedURLException from File.toURI().toURL(). toURI().toURL() almost never fails for real files, so this is a defensive guard for the rare case where the file path cannot be expressed as a valid URL.

Source

Thrown at build-tools-internal/src/main/java/org/elasticsearch/gradle/internal/packer/CacheCacheableTestFixtures.java:127

            }
        }

        private URLClassLoader createClassLoader(FileCollection classpath) {
            if (classpath == null) {
                throw new InvalidUserDataException("Missing 'classesDirs' or 'classpath' property.");
            }

            final Set<File> cpElements = new LinkedHashSet<>();
            cpElements.addAll(classpath.getFiles());
            final URL[] urls = new URL[cpElements.size()];
            try {
                int i = 0;
                for (final File cpElement : cpElements) {
                    urls[i++] = cpElement.toURI().toURL();
                }
                assert i == urls.length;
            } catch (MalformedURLException mfue) {
                throw new InvalidUserDataException("Failed to build classpath URLs.", mfue);
            }

            return URLClassLoader.newInstance(urls, ClassLoader.getSystemClassLoader());
        }

    }
}

View on GitHub (pinned to db6a809a66)

Solutions

1. Inspect the resolved classpath files (print files of the FileCollection) and look for null/non-file entries.
2. Ensure the classpath is derived from real resolved configurations (configurations.runtimeClasspath) rather than ad-hoc providers.
3. If a path is genuinely problematic, normalise/copy the artifact to a path with standard characters before building the URL.
4. Check the wrapped MalformedURLException in the stack trace to see exactly which path failed.

// Pre-validate that every classpath file produces a usable URL
for (File f : classpath.getFiles()) {
    try { f.toURI().toURL(); }
    catch (MalformedURLException e) { throw new InvalidUserDataException("Bad classpath entry: " + f, e); }
}

try {
    URL[] urls = buildUrls(classpath);
} catch (InvalidUserDataException e) {
    // surface the failing path from the wrapped MalformedURLException
    throw new GradleException("Classpath URL build failed; check resolved artifacts exist", e);
}

When it happens

Trigger: A classpath element whose File.toURI() returns a non-file/invalid URI that toURL() then rejects; typically a synthetic/placeholder file collection entry rather than a real artifact on disk.

Common situations: A custom FileCollection built from string-backed providers instead of real files; an artifact-resolved file that was deleted between configuration and execution; exotic paths with characters that break URI handling on some JVMs.

Related errors

• Cannot load VersionPropertiesBuildService
• Cannot resolve minimum compiler version via VersionPropertie
• Missing 'classesDirs' or 'classpath' property.
• Failed to build classpath URLs.
• Elasticsearch version is missing from properties.

AI-assisted analysis of elastic/elasticsearch@db6a809a66 (2026-08-12). Data as JSON: /api/errors/312b5a6ee4d54a53. Report an issue: GitHub.