skylot/jadx · error · JadxRuntimeException

Can't build insn arg from encoded value: {}

Error message

Can't build insn arg from encoded value: {}

What it means

In CustomStringConcat.buildInsnArgFromEncodedValue(), the converted constant value is not null, not a LiteralArg, not an ArgType, and not a String. The StringConcatFactory recipe constant cannot be turned into an instruction argument because its type is unrecognized.

Source

Thrown at jadx-core/src/main/java/jadx/core/dex/instructions/invokedynamic/CustomStringConcat.java:115

			concat.addArg(InsnArg.wrapArg(new ConstStringNode(sb.toString())));
		}
	}

	private static InsnArg buildInsnArgFromEncodedValue(EncodedValue encodedValue) {
		Object value = EncodedValueUtils.convertToConstValue(encodedValue);
		if (value == null) {
			return InsnArg.lit(0, ArgType.UNKNOWN);
		}
		if (value instanceof LiteralArg) {
			return ((LiteralArg) value);
		}
		if (value instanceof ArgType) {
			return InsnArg.wrapArg(new ConstClassNode((ArgType) value));
		}
		if (value instanceof String) {
			return InsnArg.wrapArg(new ConstStringNode(((String) value)));
		}
		throw new JadxRuntimeException("Can't build insn arg from encoded value: " + encodedValue);
	}
}

View on GitHub (pinned to e738a26571)

Solutions

1. Upgrade JADX.
2. Inspect the StringConcatFactory recipe and its constant values with baksmali.
3. Use --show-bad-code to continue past the failing site.
4. Report the encoded value type upstream.

// Narrow the converted value to the supported set before building an arg.
Object v = EncodedValueUtils.convertToConstValue(encodedValue);
boolean buildable = v == null || v instanceof LiteralArg || v instanceof ArgType || v instanceof String;

try {
    jadx.load();
} catch (JadxRuntimeException e) {
    if (e.getMessage().contains("Can't build insn arg from encoded value")) {
        log.warn("Unsupported constant in StringConcatFactory recipe", e);
    } else throw e;
}

When it happens

Trigger: A StringConcatFactory bootstrap call whose recipe constant value (beyond index 3) is an unexpected EncodedValue type — e.g. an enum, array, annotation, or byte/short value that EncodedValueUtils.convertToConstValue returns as an unsupported object.

Common situations: Non-standard string concatenation recipes, obfuscated or packed makeConcatWithConstants sites, or a DEX produced by a toolchain with unusual encoded constants.

Related errors

• Failed to get call site for insn: {}
• 'invoke-custom' instruction processing error: {}
• Unsupported type for raw invoke-custom: {}
• Failed to generate 'invoke-custom' instruction:
• Unexpected argument type in lambda call:

AI-assisted analysis of skylot/jadx@e738a26571 (2026-08-14). Data as JSON: /api/errors/daf05c6eb095e64a. Report an issue: GitHub.