alibaba/DataX · error · RuntimeException

TRANSFORMER_ILLEGAL_PARAMETER

TRANSFORMER_ILLEGAL_PARAMETER

Error message

dx_replace paras must be 4

What it means

Thrown by the dx_replace transformer when its paras array does not contain exactly 4 elements. dx_replace expects [columnIndex(int), startIndex(String), length(String), replaceString(String)]. The count check fires first inside the parameter-parsing try block, and the message is surfaced as TRANSFORMER_ILLEGAL_PARAMETER prefixed with the actual paras list.

Source

Thrown at core/src/main/java/com/alibaba/datax/core/transport/transformer/ReplaceTransformer.java:29

/**
 * no comments.
 * Created by liqiang on 16/3/4.
 */
public class ReplaceTransformer extends Transformer {
    public ReplaceTransformer() {
        setTransformerName("dx_replace");
    }

    @Override
    public Record evaluate(Record record, Object... paras) {

        int columnIndex;
        int startIndex;
        int length;
        String replaceString;
        try {
            if (paras.length != 4) {
                throw new RuntimeException("dx_replace paras must be 4");
            }

            columnIndex = (Integer) paras[0];
            startIndex = Integer.valueOf((String) paras[1]);
            length = Integer.valueOf((String) paras[2]);
            replaceString = (String) paras[3];
        } catch (Exception e) {
            throw DataXException.asDataXException(TransformerErrorCode.TRANSFORMER_ILLEGAL_PARAMETER, "paras:" + Arrays.asList(paras).toString() + " => " + e.getMessage());
        }

        Column column = record.getColumn(columnIndex);

        try {
            String oriValue = column.asString();

            //如果字段为空，跳过replace处理
            if(oriValue == null){
                return  record;

View on GitHub (pinned to 80ec23d5c5)

Solutions

1. Provide exactly 4 parameters in order: column index (int), startIndex (numeric string), length (numeric string), replacement string.
2. Verify the error payload: the message includes 'paras:[...]' showing what was actually parsed, so compare it against the expected 4-element shape.
3. Ensure startIndex and length are quoted numeric strings (e.g. "2", "3") and columnIndex is a bare integer.

Example fix

// before
"paras": [0, "2", "3"]
// after
"paras": [0, "2", "3", "REDACTED"]

Object[] paras = ...;
if (paras.length != 4) throw new IllegalArgumentException("dx_replace needs [columnIndex, startIndex, length, replaceString]");
// also assert types: paras[0] instanceof Integer, paras[1..2] numeric strings

When it happens

Trigger: A job JSON declares dx_replace with 3 or 5 parameters, e.g. "paras": [0, "0", "2"] (missing the replacement string) or including an extra trailing parameter. Also triggered if paras is not an array at all so its length differs from 4.

Common situations: Forgetting the final replaceString argument, mixing up dx_replace with dx_substr (which takes 3 parameters), or pasting a parameter list from a different transformer's documentation.

Related errors

• dx_pad first para(%s) support l or r
• TRANSFORMER_RUN_EXCEPTION
• TRANSFORMER_ILLEGAL_PARAMETER
• 您提供的配置文件有误. 路径[%s]需要配置Json格式的Map对象，但该节点发现实际类型是[%s]. 请检查您的配置并
• 您提供的配置文件有误. 路径[%s]值为null，datax无法识别该配置. 请检查您的配置并作出修改.

AI-assisted analysis of alibaba/DataX@80ec23d5c5 (2026-08-14). Data as JSON: /api/errors/b861dead3f28320f. Report an issue: GitHub.