stanfordnlp/CoreNLP · error · IllegalArgumentException

Unsatisfiable annotator list

Error message

Unsatisfiable annotator list: ${annotators}

What it means

ensurePrerequisiteAnnotators repeatedly removes annotators whose requirements are satisfied by others; if an entire iteration adds nothing, the requested annotator combination cannot be satisfied and it throws IllegalArgumentException 'Unsatisfiable annotator list'.

Solutions

1. Include the full prerequisite chain explicitly, e.g. tokenize,ssplit,pos,lemma,ner.
2. Let CoreNLP compute prerequisites (call ensurePrerequisiteAnnotators with the minimal intent list) instead of hand-editing.
3. Check the printed list to find which annotator's requirements are unsatisfied.
4. Upgrade CoreNLP - newer versions satisfy more combos automatically.

Example fix

// before
props.setProperty("annotators", "ner,coref"); // prerequisites missing
// after
props.setProperty("annotators", "tokenize,ssplit,pos,lemma,ner,coref");

List<String> req = new ArrayList<>(Arrays.asList("tokenize","ssplit","pos","lemma"));
for (String a : requested) if (!req.contains(a)) req.add(a);
props.setProperty("annotators", String.join(",", req));

try { pipeline = new StanfordCoreNLP(props); } catch (IllegalArgumentException e) { if (e.getMessage().startsWith("Unsatisfiable annotator list")) { log.error("Missing prerequisites in: {}", props.getProperty("annotators")); } throw e; }

When it happens

Trigger: Passing an annotators list where some required prerequisite is missing and cannot be auto-added, e.g. requesting 'ner' or 'parse' dependent combos while excluding their prerequisites, or conflicting removals leaving unsatisfied requirements.

Common situations: Hand-trimming 'annotators' to speed up pipelines and accidentally removing prerequisites like tokenize/ssplit/pos; combining annotators whose requirements conflict in the given order.

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

• Unknown annotator
• Cannot infer requirements for annotator
• Unknown LogPriorType:
• unsupported language
• no sieve type specified

AI-assisted analysis of stanfordnlp/CoreNLP@1b7edd19c4 (2026-09-10). Data as JSON: /api/errors/8a30ca3a8a413af0. Report an issue: GitHub.

Appendix: source

Thrown at src/edu/stanford/nlp/pipeline/StanfordCoreNLP.java:546

          // Weird hack to replace POS with POS tags from PARSE if we are already doing parse (and just parse)
          if (useParseForPos && Annotator.STANFORD_POS.equals(prereq)) {
            prereq = Annotator.STANFORD_PARSE;
          }
          if (!prereq.equals(candidate) && !orderedAnnotators.contains(prereq)) {
            canAdd = false;
            break;
          }
        }
        // If so, add the annotator
        if (canAdd) {
          orderedAnnotators.add(candidate);
          iter.remove();
          somethingAdded = true;
        }
      }
      // Make sure we're making progress every iteration, to prevent an infinite loop
      if (!somethingAdded) {
        throw new IllegalArgumentException("Unsatisfiable annotator list: " + StringUtils.join(annotators, ","));
      }
    }

    // Remove depparse + parse -- these are redundant
    if (orderedAnnotators.contains(STANFORD_PARSE) && !ArrayUtils.contains(annotators, STANFORD_DEPENDENCIES)) {
      orderedAnnotators.remove(STANFORD_DEPENDENCIES);
    }

    // Tweak the properties, if necessary
    // (set the mention annotator to use dependency trees, if appropriate)
    if ((orderedAnnotators.contains(Annotator.STANFORD_COREF_MENTION) || orderedAnnotators.contains(Annotator.STANFORD_COREF))
        && !orderedAnnotators.contains(Annotator.STANFORD_PARSE) &&
        !props.containsKey("coref.md.type")) {
      props.setProperty("coref.md.type", "dep");
    }
    // (ensure regexner is after ner)
    if (orderedAnnotators.contains(Annotator.STANFORD_NER) && orderedAnnotators.contains(STANFORD_REGEXNER)) {
      orderedAnnotators.remove(STANFORD_REGEXNER);

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