continuedev/continue · error · ContinueError

FindAndReplaceMissingOldString

FindAndReplaceMissingOldString

Error message

${context}string old_string is required

What it means

validateSingleEdit enforces the search/replace edit schema: old_string must be present and a string. Missing or non-string old_string throws ContinueError with code FindAndReplaceMissingOldString (message prefixed with the multi-edit index when applicable).

Source

Thrown at core/edit/searchAndReplace/findAndReplaceUtils.ts:18

import { ContinueError, ContinueErrorReason } from "../../util/errors";

export const FOUND_MULTIPLE_FIND_STRINGS_ERROR =
  "Either provide a more specific string with surrounding context to make it unique, or use replace_all=true to replace all occurrences.";

/**
 * 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(

View on GitHub (pinned to 5522c6f44c)

Solutions

1. Validate edit payloads before calling apply (required string oldString)
2. Fix the producer (prompt/tool schema) to always include old_string
3. Log the index from the message to locate the offending edit in a multi-edit

Example fix

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

edits.every(e => typeof e?.oldString === 'string' && typeof e?.newString === 'string') || failFast();

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

catch (e) { if (e instanceof ContinueError && e.code === 'FindAndReplaceMissingOldString') { reportEditIndex(e.message); } }

When it happens

Trigger: Passing an edit object without oldString, or with oldString set to null/number (e.g. from unvalidated JSON or LLM output).

Common situations: LLM emits {new_string: ...} without old_string; user scripts build edit payloads from dynamic data where the field can be undefined; schema drift between versions.

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

• FindAndReplaceMissingNewString
• 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/b1f861d946ce6c1e. Report an issue: GitHub.