appsmithorg/appsmith · error · TernDefinitionError

Failed to generate autocomplete definitions for ${name}.

Error message

Failed to generate autocomplete definitions for ${name}.

What it means

Thrown as TernDefinitionError(name) after a library has installed successfully on self, while building autocomplete (Tern) definitions via makeTernDefs(self[key]) for each accessor. If makeTernDefs throws (e.g. the installed export is a structure the def-generator cannot walk, has circular references, or triggers an unexpected type), the accessors are rolled back (self[acc] = undefined) and the install is aborted with message 'Failed to generate autocomplete definitions for ${name}.'

Source

Thrown at app/client/src/workers/Evaluation/handlers/jsLibrary.ts:239

    if (accessors.length === 0) {
      throw new Error("Unable to determine a unique accessor");
    }

    // Name of the library is the last accessor. This is totally random and needs fixing.
    const name = accessors[accessors.length - 1];

    defs["!name"] = `LIB/${name}`;
    try {
      for (const key of accessors) {
        defs[key] = makeTernDefs(self[key]);
      }
    } catch (e) {
      for (const acc of accessors) {
        self[acc] = undefined;
      }

      log.debug(e, `ternDefinitions failed for ${url}`);
      throw new TernDefinitionError(
        `Failed to generate autocomplete definitions: ${name}`,
      );
    }

    // Restore the libraries from libStore to the global scope.
    // This is done to ensure that the libraries are not overwritten by the newly installed library.
    Object.keys(libStore).forEach((k) => (self[k] = libStore[k]));

    //Reserve accessor names.
    for (const acc of accessors) {
      //we have to update invalidEntityIdentifiers as well
      libraryReservedIdentifiers[acc] = true;
      invalidEntityIdentifiers[acc] = true;
    }

    return { success: true, defs, accessor: accessors };
  } catch (error) {
    addTempStoredDataTreeToContext(tempDataTreeStore);

View on GitHub (pinned to 8cd9021c24)

Solutions

1. Try a different build of the same library (UMD vs ESM, or an earlier version) whose top-level export is a plain object/function.
2. Pin to the last version that installed successfully if a recent release regressed.
3. If only part of the library is needed, load a smaller subpath build that exposes a simpler export.
4. Report the failing accessor/export shape so makeTernDefs can be hardened; the underlying thrown error is logged at debug level as 'ternDefinitions failed for ${url}'.

Example fix

// before
https://cdn.jsdelivr.net/npm/heavylib@latest/dist/heavylib.full.js  // circular export breaks makeTernDefs

// after
https://cdn.jsdelivr.net/npm/heavylib@2.3.0/dist/heavylib.core.js  // simpler export shape

// No safe pre-check for makeTernDefs failure; validate the export shape is simple.
async function exportShape(url) {
  const m = await import(/* webpackIgnore: true */ url).catch(() => null);
  if (!m) return 'no-module';
  try { JSON.stringify(m.default ?? m); return 'serializable'; }
  catch { return 'cyclic-or-non-serializable'; }
}

const isPlainSerializable = (v, seen = new WeakSet()) => {
  if (v === null || typeof v !== 'object') return true;
  if (seen.has(v)) return false; // cycle
  seen.add(v);
  return Object.values(v).every(val => isPlainSerializable(val, seen));
};

try {
  await installLibrary(url);
} catch (e) {
  if (e?.name === 'TernDefinitionError') {
    // Fallback: try an alternate build/version with a simpler export
    await installLibrary(alternateUrlFor(url));
  } else throw e;
}

When it happens

Trigger: Installing a library whose top-level export contains deeply recursive, non-enumerable, or proxy/getter-heavy structures that break makeTernDefs; a build whose default export is a class instance with unusual prototype shape; an export whose typeof causes an unhandled branch in the def walker.

Common situations: Large frameworks (e.g. some ML/graph libs) with circular self-references; minified bundles that expose exotic object shapes; a library version whose entry export changed shape from a prior working version.

Related errors

• The script at ${url} cannot be installed.
• Unable to determine a unique accessor
• Unable to generate a unique accessor
• Failed to load JS libraries
• Found a Promise() during evaluation. Data fields cannot exec

AI-assisted analysis of appsmithorg/appsmith@8cd9021c24 (2026-08-12). Data as JSON: /api/errors/da599adf6c5991f3. Report an issue: GitHub.