shwenzhang/AndResGuard · error · brut.androlib.AndrolibException

Config size < 28

Error message

Config size < 28

What it means

RawARSCDecoder.readConfigFlags mirrors ARSCDecoder's check in the raw name-collection pass: each TYPE config must declare a size of at least 28 bytes (the minimal ResTable_config). A smaller value means the config chunk is malformed or the raw stream is misaligned, so the pre-scan of the arsc aborts.

Solutions

1. Rebuild the APK's resources.arsc with official aapt/aapt2 and retry
2. Start from the original, unmodified APK rather than a repacked one
3. Validate with aapt dump resources to locate the malformed config
4. Upgrade AndResGuard for broader arsc compatibility

Example fix

// before: repacked apk from a third-party store tool
AndResGuard.process(repackedApk)
// after: use the original build artifact
AndResGuard.process(originalReleaseApk)

// validate arsc before the raw name pre-scan
// aapt dump resources app.apk — aborts the pipeline if the arsc is malformed

try {
  RawARSCDecoder.decode(arscStream);
} catch (AndrolibException e) {
  if (e.getMessage().contains("Config size < 28")) {
    throw new BuildException("Malformed arsc config; rebuild with official aapt2", e);
  }
  throw e;
}

When it happens

Trigger: During readConfig -> readConfigFlags, mIn.readInt() returns a config size < 28, caused by a non-standard/malformed resources.arsc or by earlier chunks being consumed with wrong lengths in the raw pass.

Common situations: APKs repacked by third-party tools, arsc files built with non-aapt generators, corrupted downloads, or double-processed (already obfuscated) APKs.

Understand the failure class

Background: "Invalid value" and "allowed values are" config errors: what your library rejected and how to fix it — this error's family across 41 libraries.

Related errors

• Config size < 28
• Could not decode arsc file
• Invalid chunk type: expected=0x%08x, got=0x%08x
• Invalid chunk type: expected=
• readAndWriteHeader size < 0: size=

AI-assisted analysis of shwenzhang/AndResGuard@e4df245d82 (2026-09-12). Data as JSON: /api/errors/f3a2b0d27c533bfa. Report an issue: GitHub.

Appendix: source

Thrown at AndResGuard-core/src/main/java/com/tencent/mm/androlib/res/decoder/RawARSCDecoder.java:241

      mIn.readInt();
      readValue(flags, specNamesId);
    }
  }

  private void readValue(boolean flags, int specNamesId) throws IOException, AndrolibException {
    /* size */
    mIn.skipCheckShort((short) 8);
    /* zero */
    mIn.skipCheckByte((byte) 0);
    byte type = mIn.readByte();
    int data = mIn.readInt();
  }

  private void readConfigFlags() throws IOException, AndrolibException {
    int read = 28;
    int size = mIn.readInt();
    if (size < 28) {
      throw new AndrolibException("Config size < 28");
    }

    boolean isInvalid = false;
    short mcc = mIn.readShort();
    short mnc = mIn.readShort();
    char[] language = new char[] { (char) mIn.readByte(), (char) mIn.readByte() };
    char[] country = new char[] { (char) mIn.readByte(), (char) mIn.readByte() };
    byte orientation = mIn.readByte();
    byte touchscreen = mIn.readByte();
    int density = mIn.readUnsignedShort();
    byte keyboard = mIn.readByte();
    byte navigation = mIn.readByte();
    byte inputFlags = mIn.readByte();
    /* inputPad0 */
    mIn.skipBytes(1);

    short screenWidth = mIn.readShort();
    short screenHeight = mIn.readShort();

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