stanfordnlp/CoreNLP · error · UnsupportedOperationException

Dependencies type not implemented

Error message

Dependencies type not implemented: <commandArgs>

What it means

LexicalizedParserServer.handleDependencies() only implements the COLLAPSED_TREE dependencies type; any other command argument hits the switch default and throws UnsupportedOperationException. The server exposes just one dependency-output flavor for this endpoint.

Solutions

1. Send exactly COLLAPSED_TREE as the dependencies type argument.
2. Upgrade both client and server to a CoreNLP version supporting the dependency format you need.
3. Compute other dependency styles client-side from a parsed tree (typedDependencies in your own code).
4. Patch/extend handleDependencies in a local fork if you need additional formats.

Example fix

// before
String resp = client.query("deps", "basic", sentence);
// after
String resp = client.query("deps", "COLLAPSED_TREE", sentence);

if (!"COLLAPSED_TREE".equalsIgnoreCase(depsType))
    throw new IllegalArgumentException("Server supports only COLLAPSED_TREE deps type, got: " + depsType);

try {
    String resp = client.query("deps", depsType, sentence);
} catch (UnsupportedOperationException e) {
    if (e.getMessage().startsWith("Dependencies type not implemented")) {
        // fall back to COLLAPSED_TREE
    }
}

When it happens

Trigger: Sending a server request 'deps' (or similar) with a commandArgs value other than COLLAPSED_TREE, e.g. 'TREE', 'COLLAPSED', 'BASIC', or a lowercase-variant bug (uppercase conversion is applied, so casing is fine).

Common situations: Clients built against newer CoreNLP APIs (which support basic/collapsed/semicolon formats) talking to an older server, or guessing argument names not in the switch.

Related errors

• : Does not support parse operation.
• Cannot set from string
• Cannot set from string
• This version of the parser does not support non-tree…
• This version of the parser does not support non-tree…

AI-assisted analysis of stanfordnlp/CoreNLP@1b7edd19c4 (2026-09-10). Data as JSON: /api/errors/e0c0eb98f5e0ed82. Report an issue: GitHub.

Appendix: source

Thrown at src/edu/stanford/nlp/parser/server/LexicalizedParserServer.java:229

  // TODO: when this method throws an exception (for whatever reason)
  // a waiting client might hang.  There should be some graceful
  // handling of that.
  public void handleDependencies(String arg, OutputStream outStream, String commandArgs) 
    throws IOException
  {
    Tree tree = parse(arg, false);
    if (tree == null) {
      return;
    }
    // TODO: this might throw an exception if the parser doesn't support dependencies.  Handle that cleaner?
    GrammaticalStructure gs = parser.getTLPParams().getGrammaticalStructure(tree, parser.treebankLanguagePack().punctuationWordRejectFilter(), parser.getTLPParams().typedDependencyHeadFinder());
    Collection<TypedDependency> deps = null;
    switch (commandArgs.toUpperCase()) {
    case "COLLAPSED_TREE":
      deps = gs.typedDependenciesCollapsedTree();
      break;
    default:
      throw new UnsupportedOperationException("Dependencies type not implemented: " + commandArgs);
    }
    OutputStreamWriter osw = new OutputStreamWriter(outStream, "utf-8");
    for (TypedDependency dep : deps) {
      osw.write(dep.toString());
      osw.write("\n");
    }
    osw.flush();
  }

  /**
   * Returns the result of applying the parser to arg as a serialized tree.
   */
  public void handleTree(String arg, OutputStream outStream) 
    throws IOException
  {
    Tree tree = parse(arg, false);
    if (tree == null) {
      return;

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