pxb1988/dex2jar · error · CantNotFixContentException

a

Error message

a

What it means

CodeWriter's packed-switch/sparse-switch payload builder validates that switch targets form a contiguous register range starting at args[0]. When args[i] != start + i for some entry, it throws CantNotFixContentException with key 'a', meaning the register arguments cannot be encoded as the required consecutive sequence.

Solutions

1. Renumber/compact the target registers so they are strictly consecutive starting at args[0]
2. Ensure args[0] is a valid ushort start register and length matches args.length-1
3. Check the register allocator: re-run allocation after any dead-register elimination

Example fix

// before
writeSwitch(op, new int[]{0, 2, 3});
// after
writeSwitch(op, new int[]{0, 1, 2});

static boolean isConsecutive(int[] args) {
    for (int i = 1; i < args.length; i++) if (args[i] != args[0] + i) return false;
    return true;
}

try { codeWriter.writeSwitch(op, args); } catch (CantNotFixContentException e) { /* renumber registers and retry */ }

When it happens

Trigger: Calling CodeWriter's switch-instruction API with register args that are not consecutive (e.g. v0, v2, v3 instead of v0, v1, v2), or with a start register whose value plus index overflows/misses a subsequent register number.

Common situations: Code generators translating high-level switch statements into dex register arrays after register reallocation; optimizations that removed registers without compacting the list; hand-built args arrays.

Understand the failure class

Background: "Must be a positive integer", "Invalid value", "Unsupported": the invalid-argument-value error family, when a library rejects the value you pass — this error's family across 35 libraries.

Related errors

• while accept code in method
• zero-width instruction op=0x%02x
• jump out of insns -> %04x
• bad payload for
• bad payload offset for

AI-assisted analysis of pxb1988/dex2jar@b5bda4fb49 (2026-09-08). Data as JSON: /api/errors/5b2a00691109db48. Report an issue: GitHub.

Appendix: source

Thrown at dex-writer/src/main/java/com/googlecode/d2j/dex/writer/CodeWriter.java:851

    // AA|op BBBB CCCC HHHH
    public static class OP4rcc extends OpInsn {
        final BaseItem mtd;
        final BaseItem proto;
        final int length;
        final int start;

        public OP4rcc(Op op, int[] args, BaseItem mtd, BaseItem proto) {
            super(op);
            this.mtd = mtd;
            this.proto = proto;
            length = args.length;
            checkContentUByte(op, "AA", length);
            if (length > 0) {
                start = args[0];
                checkContentUShort(op, "CCCC", start);
                for (int i = 1; i < args.length; i++) {
                    if (start + i != args[i]) {
                        throw new CantNotFixContentException(op, "a", args[i]);
                    }
                }
            } else {
                start = 0;
            }

        }

        @Override
        public void write(ByteBuffer out) {
            checkContentUShort(op, "@BBBB", mtd.index);
            checkContentUShort(op, "@HHHH", proto.index);
            out
                    .put((byte) op.opcode).put((byte) length) //
                    .putShort((short) mtd.index) //
                    .putShort((short) start) //
                    .putShort((short) proto.index) //
            ;

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