# `react-doctor/zod-v4-no-deprecated-error-apis`

Replace deprecated ZodError helpers with Zod 4 functions: z.treeifyError(), z.flattenError(), z.prettifyError(), or read error.issues directly

- **Status:** Active
- **Category:** Architecture
- **Assessment:** Evidence-required risk
- **Required evidence:** source code, repository context
- **Default configuration:** Enabled
- **Default severity:** warn
- **Scope:** All supported frameworks
- **Active when:** always
- **Requirements:** zod:4
- **Tags:** migration-hint
- **Priority:** 34 (P3)
- **Source:** oxlint-plugin-react-doctor
- **Rule set:** oxlint-plugin-react-doctor 0.9.3 (prompt schema 2)
- **Documentation:** [Official documentation](https://zod.dev/error-formatting)

## Validation prompt

Confirm the detector match and collect the required evidence before deciding whether an edit is warranted.

Fires in two cases: (a) on a standalone `ZodError.create(...)` call even with NO member access: the CallExpression handler reports unconditionally for any isZodErrorCreateCall, so `const error = z.ZodError.create([]);` alone produces a diagnostic; or (b) when a member named addIssue, addIssues, errors, flatten, formErrors, or format is accessed DIRECTLY off a freshly-constructed ZodError value, i.e. `new ZodError(...).<member>` or `ZodError.create(...).<member>` (computed access like `new ZodError([])["flatten"]()` and `["errors"]` also counts). Note the asymmetry: there is NO NewExpression visitor, so a bare `new ZodError([])` with no member access does NOT fire, while a bare `ZodError.create([])` DOES. The ZodError identifier/namespace member must resolve to an import from the "zod" module (covers `import { ZodError }`, `import { ZodError as ValidationError }`, and `new zod.ZodError(...)`/`zod.ZodError.create(...)`). False positives to suppress: it does NOT and should NOT fire on a ZodError held in a variable, including a caught `catch (error)` narrowed by `error instanceof ZodError` then calling `error.flatten()`/`error.errors` (no flow analysis in v1), on any error-like value of unknown origin (`getError().flatten()`), or on a `ZodError` imported from a non-zod path such as `import { ZodError } from "./errors"`: so do not flag deprecated-looking member names unless the receiver is a direct `new ZodError`/`ZodError.create` whose binding traces to "zod".

## Evidence boundary

The diagnostic proves only that the detector's modeled source pattern matched. It does not prove runtime impact, product intent, rendered failure, or that one remediation is correct.

Establish the environment, explicit repository policy, relevant exceptions, and required rendered or runtime evidence before deciding the occurrence. This page’s Assessment and Required evidence fields define the review contract.

Default severity is registry metadata. Use the occurrence's JSON severity after repository configuration when ordering real findings.

Record one outcome:

- **Confirmed failure:** The required evidence establishes the violation.
- **Rejected:** A documented exception or false-positive predicate applies.
- **Needs evidence:** Named evidence can still be collected.
- **Unavailable:** Required evidence cannot be collected in this run.
- **Waived with evidence:** An authorized, scoped exception applies to an established failure.
- **Observation:** The review records an optional tradeoff without claiming a defect.

A waiver records its scope, authority, evidence, and review or expiry condition. It is not a pass or false positive.

## Fix prompt

Apply this candidate correction only after the required evidence confirms the risk.

Migrate to the Zod 4 top-level error helpers instead of the removed/deprecated ZodError instance members: replace `err.flatten()` with `z.flattenError(err)`, `err.format()` with `z.treeifyError(err)`, `err.formErrors` with `z.flattenError(err)` and read `.formErrors`, and read validation problems via `err.issues` rather than the old `.errors`; drop `addIssue`/`addIssues` mutation in favor of constructing the issues array up front. Capture the error in a variable first (`const err = ...; z.flattenError(err)`) rather than chaining the helper off the constructor. See https://zod.dev/error-formatting

## Repository-wide copy prompt

Use this only for a repository-wide pass after validating each occurrence. For one occurrence, use the occurrence-level guidance above.

````text
Fix every confirmed `react-doctor/zod-v4-no-deprecated-error-apis` diagnostic in the current repository.

Required change:
- Migrate to the Zod 4 top-level error helpers instead of the removed/deprecated ZodError instance members: replace `err.flatten()` with `z.flattenError(err)`, `err.format()` with `z.treeifyError(err)`, `err.formErrors` with `z.flattenError(err)` and read `.formErrors`, and read validation problems via `err.issues` rather than the old `.errors`; drop `addIssue`/`addIssues` mutation in favor of constructing the issues array up front. Capture the error in a variable first (`const err = ...; z.flattenError(err)`) rather than chaining the helper off the constructor. See https://zod.dev/error-formatting.

Validation before editing:
Fires in two cases: (a) on a standalone `ZodError.create(...)` call even with NO member access: the CallExpression handler reports unconditionally for any isZodErrorCreateCall, so `const error = z.ZodError.create([]);` alone produces a diagnostic; or (b) when a member named addIssue, addIssues, errors, flatten, formErrors, or format is accessed DIRECTLY off a freshly-constructed ZodError value, i.e. `new ZodError(...).<member>` or `ZodError.create(...).<member>` (computed access like `new ZodError([])["flatten"]()` and `["errors"]` also counts). Note the asymmetry: there is NO NewExpression visitor, so a bare `new ZodError([])` with no member access does NOT fire, while a bare `ZodError.create([])` DOES. The ZodError identifier/namespace member must resolve to an import from the "zod" module (covers `import { ZodError }`, `import { ZodError as ValidationError }`, and `new zod.ZodError(...)`/`zod.ZodError.create(...)`). False positives to suppress: it does NOT and should NOT fire on a ZodError held in a variable, including a caught `catch (error)` narrowed by `error instanceof ZodError` then calling `error.flatten()`/`error.errors` (no flow analysis in v1), on any error-like value of unknown origin (`getError().flatten()`), or on a `ZodError` imported from a non-zod path such as `import { ZodError } from "./errors"`: so do not flag deprecated-looking member names unless the receiver is a direct `new ZodError`/`ZodError.create` whose binding traces to "zod".

Constraints:
- Make the smallest change that fixes the root cause.
- Preserve behavior and interfaces unrelated to this diagnostic.
- Reuse existing project components, utilities, and conventions.
- Adapt identifiers and framework details instead of copying blindly.
- Do not disable the rule or suppress matching code.

Assessment:
- Record detector evidence, applicability facts, assumptions, missing evidence, and the rule class for this occurrence.
- Return one outcome: Confirmed failure, Rejected, Needs evidence, Unavailable, Waived with evidence, or Observation.
- A waiver records the established failure, scope, authority, evidence, and review or expiry condition. It is not a pass or false positive.

Verification:
- Run focused tests for the changed behavior.
- Run React Doctor and confirm this diagnostic no longer appears from changed code.
- Run an unfiltered scan of the affected scope before claiming no cross-category regression.
- Report the files changed and any checks you could not run.
````