skylot/jadx · critical · JadxRuntimeException

Can't load classpath file:

Error message

Can't load classpath file: 

What it means

Thrown by ClsSet.loadFromClstFile when the bundled classpath resource (core.jcst at path /clst/core.jcst) is not found on the classpath. The resource is loaded via getResourceAsStream and a null return means the jcst file is missing from the jadx-core JAR or classpath. This is a packaging/classpath integrity error, not an input-file error.

Source

Thrown at jadx-core/src/main/java/jadx/core/clsp/ClsSet.java:78

	}

	private enum TypeEnum {
		WILDCARD,
		GENERIC,
		GENERIC_TYPE_VARIABLE,
		OUTER_GENERIC,
		OBJECT,
		ARRAY,
		PRIMITIVE
	}

	private ClspClass[] classes;

	public void loadFromClstFile() throws IOException, DecodeException {
		long startTime = System.currentTimeMillis();
		try (InputStream input = ClsSet.class.getResourceAsStream(CLST_PATH)) {
			if (input == null) {
				throw new JadxRuntimeException("Can't load classpath file: " + CLST_PATH);
			}
			load(input);
		}
		if (LOG.isDebugEnabled()) {
			long time = System.currentTimeMillis() - startTime;
			int methodsCount = Stream.of(classes).mapToInt(clspClass -> clspClass.getMethodsMap().size()).sum();
			LOG.debug("Clst file loaded in {}ms, android api: {}, classes: {}, methods: {}",
					time, androidApiLevel, classes.length, methodsCount);
		}
	}

	public void loadFrom(RootNode root) {
		List<ClassNode> list = root.getClasses(true);
		Map<String, ClspClass> names = new HashMap<>(list.size());
		int k = 0;
		for (ClassNode cls : list) {
			ArgType clsType = cls.getClassInfo().getType();
			String clsRawName = clsType.getObject();

View on GitHub (pinned to e738a26571)

Solutions

1. Verify that core.jcst exists inside the jadx-core JAR: jar tf jadx-core-*.jar | grep clst/core.jcst.
2. If missing, rebuild jadx-core from source with the standard Gradle build which bundles the resource, or use the official released JAR.
3. If shading/relocating, configure the shade plugin to include all resources, not just .class files.
4. Ensure the jadx-core JAR on the classpath is not corrupted — re-download or rebuild if CRC errors appear.

// Verify the core.jcst resource exists on the classpath before calling loadFromClstFile
try (InputStream check = ClsSet.class.getResourceAsStream("/clst/core.jcst")) {
    if (check == null) {
        throw new IllegalStateException("core.jcst not found on classpath — jadx-core JAR may be corrupted or mis-packaged");
    }
}

try {
    clsSet.loadFromClstFile();
} catch (JadxRuntimeException e) {
    if (e.getMessage().startsWith("Can't load classpath file:")) {
        throw new IllegalStateException("jadx-core is missing its bundled core.jcst resource. "
            + "Rebuild or re-download the jadx-core JAR.", e);
    }
    throw e;
}

When it happens

Trigger: Jadx-core JAR is repackaged or shaded without including the /clst/core.jcst resource. A custom build excluded the resource from the JAR. Running against a corrupted or truncated jadx-core JAR where the resource entry is absent. Using jadx as a library with a minimal classpath that omits the resource directory.

Common situations: Custom Maven/Gradle builds that fat-jar jadx without preserving resources. Modifying the jadx build to relocate or filter resources. A broken jadx installation where core.jcst was deleted from the JAR. CI environments with classpath shading plugins that strip non-class resources.

Related errors

• Duplicate class:
• Missing class:
• Unexpected input file:
• Unknown file format:
• Cannot save type:

AI-assisted analysis of skylot/jadx@e738a26571 (2026-08-14). Data as JSON: /api/errors/eaa00d464a5d4547. Report an issue: GitHub.