zxing/zxing · error · IllegalArgumentException

Illegal contents

Error message

Illegal contents

What it means

Error "Illegal contents" thrown in zxing/zxing.

Source

Thrown at core/src/main/java/com/google/zxing/oned/UPCEWriter.java:62

    int length = contents.length();
    switch (length) {
      case 7:
        // No check digit present, calculate it and add it
        int check;
        try {
          check = UPCEANReader.getStandardUPCEANChecksum(UPCEReader.convertUPCEtoUPCA(contents));
        } catch (FormatException fe) {
          throw new IllegalArgumentException(fe);
        }
        contents += check;
        break;
      case 8:
        try {
          if (!UPCEANReader.checkStandardUPCEANChecksum(UPCEReader.convertUPCEtoUPCA(contents))) {
            throw new IllegalArgumentException("Contents do not pass checksum");
          }
        } catch (FormatException ignored) {
          throw new IllegalArgumentException("Illegal contents");
        }
        break;
      default:
        throw new IllegalArgumentException(
            "Requested contents should be 7 or 8 digits long, but got " + length);
    }

    checkNumeric(contents);

    int firstDigit = Character.digit(contents.charAt(0), 10);
    if (firstDigit != 0 && firstDigit != 1) {
      throw new IllegalArgumentException("Number system must be 0 or 1");
    }

    int checkDigit = Character.digit(contents.charAt(7), 10);
    int parities = UPCEReader.NUMSYS_AND_CHECK_DIGIT_PATTERNS[firstDigit][checkDigit];
    boolean[] result = new boolean[CODE_WIDTH];

View on GitHub (pinned to 19aa2d8254)

Solutions

1. Supply numeric contents of valid length for UPC-E encoding.
2. Sanitize the input to remove characters that are not digits.

When it happens

Trigger: Thrown at core/src/main/java/com/google/zxing/oned/UPCEWriter.java:62 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of zxing/zxing@19aa2d8254 (2026-08-14). Data as JSON: /api/errors/a10a2ca59b75aa5f. Report an issue: GitHub.