continuedev/continue · error · ContinueError

FindAndReplaceMissingNewString

FindAndReplaceMissingNewString

Error message

${context}string new_string is required

What it means

validateSingleEdit also requires new_string to be present and a string; otherwise it throws ContinueError with code FindAndReplaceMissingNewString. Note the preceding check throws first, so this fires only when old_string was valid but new_string is missing/non-string.

Source

Thrown at core/edit/searchAndReplace/findAndReplaceUtils.ts:24

/**
 * Validates a single edit operation
 */
export function validateSingleEdit(
  oldString: unknown,
  newString: unknown,
  replaceAll: unknown,
  index?: number,
): { oldString: string; newString: string; replaceAll?: boolean } {
  const context = index !== undefined ? `edit at index ${index}: ` : "";

  if (oldString === undefined || typeof oldString !== "string") {
    throw new ContinueError(
      ContinueErrorReason.FindAndReplaceMissingOldString,
      `${context}string old_string is required`,
    );
  }
  if (newString === undefined || typeof newString !== "string") {
    throw new ContinueError(
      ContinueErrorReason.FindAndReplaceMissingNewString,
      `${context}string new_string is required`,
    );
  }
  if (oldString === newString) {
    throw new ContinueError(
      ContinueErrorReason.FindAndReplaceIdenticalOldAndNewStrings,
      `${context}old_string and new_string must be different`,
    );
  }
  if (replaceAll !== undefined && typeof replaceAll !== "boolean") {
    throw new ContinueError(
      ContinueErrorReason.FindAndReplaceInvalidReplaceAll,
      `${context}replace_all must be a valid boolean`,
    );
  }
  return { oldString, newString, replaceAll };
}

View on GitHub (pinned to 5522c6f44c)

Solutions

1. Always include newString (use "" for deletions)
2. Validate payloads with a schema/type guard before applying
3. Fix tool prompt/spec to mark new_string as required

Example fix

// before
applyEdits([{ oldString: "y" }]);
// after
applyEdits([{ oldString: "y", newString: "" }]);

if (typeof edit.newString !== 'string') edit.newString = ''; // normalize deletions

const isValidEdit = (e: unknown): e is { oldString: string; newString: string } =>
  typeof (e as any)?.oldString === 'string' && typeof (e as any)?.newString === 'string';

catch (e) { if (e instanceof ContinueError && e.code === 'FindAndReplaceMissingNewString') { fill newString='' and revalidate; } }

When it happens

Trigger: Edit payloads where oldString is a valid string but newString is undefined/null/non-string — commonly an LLM emitting a pure deletion without new_string or malformed JSON.

Common situations: LLM tool calls omitting new_string for deletions (should be empty string); dynamic payload construction; consumers assuming newString is optional.

Understand the failure class

Background: Schema validation failed / invalid input schema: payload rejected because its shape doesn't match the expected schema — this error's family across 28 libraries.

Related errors

• FindAndReplaceMissingOldString
• Hunk could not be applied cleanly to source code.
• FindAndReplaceIdenticalOldAndNewStrings
• Failed to parse config: ${formatZodError(e)}
• No edit snippet provided.

AI-assisted analysis of continuedev/continue@5522c6f44c (2026-08-27). Data as JSON: /api/errors/9672d0bfa4dea38e. Report an issue: GitHub.