stanfordnlp/CoreNLP · error · RuntimeException

Error: Line has too few tab-separated columns (${maxColumns}

Error message

Error: Line has too few tab-separated columns (${maxColumns}) for ${flags.length} columns required by specified properties: ${line}

What it means

After per-line checks pass, readDataset verifies each line has at least as many tab-separated columns as the number of feature properties (flags.length) configured. A line with fewer columns cannot supply values for all configured features, so it throws a RuntimeException reporting the observed max column count and the offending line. Note the count shown is maxColumns (the widest line seen), not the offending line's width.

Solutions

1. Add the missing tab-separated columns to the offending line so it matches flags.length
2. Reduce the column mappings in your properties file to match the data's actual column count
3. Verify delimiters are real tabs (the splitter is tab-based)

Example fix

// before (3 columns, properties need 4)
label	f1	f2
// after
label	f1	f2	f3

int minCols = lines.stream().mapToInt(l -> l.split("\t", -1).length).min().orElse(0); if (minCols < flagsCount) throw new IllegalStateException("File has only " + minCols + " columns, need " + flagsCount);

null

try { readDataset(path); } catch (RuntimeException e) { log.error("Column count mismatch between properties and data: " + e.getMessage(), e); }

When it happens

Trigger: Running readDataset (via dataInfo or readTestExamples) when the properties file defines more feature columns (e.g. columns 0..N) than some data line provides tab-separated fields.

Common situations: Mismatch between the properties file's column definitions and the actual TSV; a short row in the middle of the file; switching to a test file with fewer columns without updating properties.

Understand the failure class

Background: "Invalid ... format", "must be in format X", "does not look like a ..." — invalid argument format errors across CLI tools and libraries — this error's family across 17 libraries.

Related errors

• Line format error at line ${lineNo}: ${line}
• Dataset could not be loaded
• Not enough columns for format ${format}
• Unrecognized format specification in ${format}
• addFeature was called with a features object that is neither

AI-assisted analysis of stanfordnlp/CoreNLP@1b7edd19c4 (2026-09-10). Data as JSON: /api/errors/a123f4b7626173b0. Report an issue: GitHub.

Appendix: source

Thrown at src/edu/stanford/nlp/classify/ColumnDataClassifier.java:467

            if (line.matches("\\s#.*")) {
              continue;
            }
          }
          String[] strings = splitLineToFields(line);
          if (strings.length < 2) {
            throw new RuntimeException("Line format error at line " + lineNo + ": " + line);
          }
          if (strings.length < minColumns) {
            minColumns = strings.length;
          }
          if (strings.length > maxColumns) {
            maxColumns = strings.length;
          }
          if (inTestPhase) {
            lineInfos.add(strings);
          }
          if (strings.length < flags.length) {
            throw new RuntimeException("Error: Line has too few tab-separated columns (" + maxColumns +
                    ") for " + flags.length + " columns required by specified properties: " + line);
          }
          dataset.add(makeDatumFromStrings(strings));
        }
        if (lineNo > 0 && minColumns != maxColumns) {
          logger.info("WARNING: Number of tab-separated columns in " +
                  filename + " varies between " + minColumns + " and " + maxColumns);
        }
      } catch (Exception e) {
        throw new RuntimeException("Dataset could not be loaded", e);
      }
    }
    logger.info("Reading dataset from " + filename + " ... done [" + tim.toSecondsString() + "s, " + dataset.size() + " items].");
    return new Pair<>(dataset, lineInfos);
  }

  /** Split according to whether we are using tsv file (default) or csv files. */
  private String[] splitLineToFields(String line) {

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