prestodb/presto · error · IllegalArgumentException

pad must not be in alphabet or whitespace

Error message

pad must not be in alphabet or whitespace

What it means

Argument validation in the Base32 codec constructor: the configured padding byte (or a byte in the line separator overlap check) is also a member of the encoding alphabet or is whitespace. Because the pad character must be unambiguous for decode, the codec refuses the configuration at construction time.

Source

Thrown at presto-common/src/main/java/com/facebook/presto/common/type/encoding/Base32.java:308

                throw new IllegalArgumentException("lineLength " + lineLength + " > 0, but lineSeparator is null");
            }
            // Must be done after initializing the tables
            if (containsAlphabetOrPad(lineSeparator)) {
                final String sep = StringUtils.newStringUtf8(lineSeparator);
                throw new IllegalArgumentException("lineSeparator must not contain Base32 characters: [" + sep + "]");
            }
            this.encodeSize = BYTES_PER_ENCODED_BLOCK + lineSeparator.length;
            this.lineSeparator = new byte[lineSeparator.length];
            System.arraycopy(lineSeparator, 0, this.lineSeparator, 0, lineSeparator.length);
        }
        else {
            this.encodeSize = BYTES_PER_ENCODED_BLOCK;
            this.lineSeparator = null;
        }
        this.decodeSize = this.encodeSize - 1;

        if (isInAlphabet(pad) || isWhiteSpace(pad)) {
            throw new IllegalArgumentException("pad must not be in alphabet or whitespace");
        }
    }

    /**
     * <p>
     * Decodes all of the provided data, starting at inPos, for inAvail bytes. Should be called at least twice: once
     * with the data to decode, and once with inAvail set to "-1" to alert decoder that EOF has been reached. The "-1"
     * call is not necessary when decoding, but it doesn't hurt, either.
     * </p>
     * <p>
     * Ignores all non-Base32 characters. This is how chunked (e.g. 76 character) data is handled, since CR and LF are
     * silently ignored, but has implications for other bytes, too. This method subscribes to the garbage-in,
     * garbage-out philosophy: it will not check the provided data for validity.
     * </p>
     *
     * @param in byte[] array of ascii data to Base32 decode.
     * @param inPos Position to start reading data from.
     * @param inAvail Amount of bytes available from input for encoding.

View on GitHub (pinned to 55bb57d202)

Solutions

1. Choose a pad byte outside the alphabet and whitespace
2. Use the default '=' pad character

When it happens

Trigger: Thrown at presto-common/src/main/java/com/facebook/presto/common/type/encoding/Base32.java:308 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of prestodb/presto@55bb57d202 (2026-09-04). Data as JSON: /api/errors/2a1459bca82336a4. Report an issue: GitHub.