Zod 4 enum error messages omitting "received X" part #4339

dirkluijk · 2025-05-08T09:21:02Z

I wanted to check out the new prettifyError utility of Zod 4. When checking its implementation in @zod/core, I realized it is also compatible with Zod 3; except for a type-cast.

To prove it, I ran the following script:

import { z, ZodError } from "zod";
import { prettifyError } from "@zod/core";

const MyEnum = z.enum(["FOO", "BAR"]);
const MyNativeEnum = z.nativeEnum({ FOO: "FOO", BAR: "BAR" } as const);
const MyUnion = z.union([z.literal("FOO"), z.literal("BAR")]);

const TEST_CASES = [
  [`Enum 'INVALID' (pretty-printed)`, async () => MyEnum.parse("INVALID")],
  [`NativeEnum 'INVALID' (pretty-printed)`, async () => MyNativeEnum.parse("INVALID")],
  [`Union 'INVALID' (pretty-printed)`, async () => MyUnion.parse("INVALID")],
] as const;

async function prettify<T extends string>(fn: () => T | PromiseLike<T>): Promise<T | string> {
  try {
    return await fn();
  } catch (error) {
    if (error instanceof ZodError) {
      return prettifyError(error as any); // type-cast needed when using Zod 3
    }

    throw error;
  }
}

for (const [name, fn] of TEST_CASES) {
  console.log(`${name}:`);
  console.log(await prettify(() => fn()));
  console.log("---");
}

I noticed a small behavior difference.

Zod 3:

Enum 'INVALID' (pretty-printed):
✖ Invalid enum value. Expected 'FOO' | 'BAR', received 'INVALID'
---
NativeEnum 'INVALID' (pretty-printed):
✖ Invalid enum value. Expected 'FOO' | 'BAR', received 'INVALID'
---
Union 'INVALID' (pretty-printed):
✖ Invalid input
---

Zod 4:

Enum 'INVALID' (pretty-printed):
✖ Invalid option: expected one of "FOO"|"BAR"
---
NativeEnum 'INVALID' (pretty-printed):
✖ Invalid option: expected one of "FOO"|"BAR"
---
Union 'INVALID' (pretty-printed):
✖ Invalid input
---

My questions:

Is this difference intended?
Is there a way to get rid of the type-cast?
What is the recommended way to type things and be compatible with both Zod 3 and 4 as peer dependency, or is that simply not recommended?

The text was updated successfully, but these errors were encountered:

colinhacks · 2025-05-15T01:19:51Z

The change you're referring to was intentional. Zod has a policy of not logging any user input by default, which is (partially) why there's no input field in issues.

As a compromise, you're now able to access the input inside custom error maps:

const myEnum = z.enum(["a", "b", "c"], {
  error: (iss): string => `Expected ${Object.values(myEnum.def.entries)}, received ${iss.input}`,
});

myEnum.parse("d");
// => 'Expected a,b,c, received d'

Thanks for the idea! I've loosened the input type for prettifyError to make it compatible with both v3 and v4. Very nice :)

--

Re compat: The most recent betas have been significantly restructured to make it easier for projects/libraries to incrementally migrate to Zod 4. Details here: #4364

dirkluijk · 2025-05-15T18:13:37Z

Thanks @colinhacks ! ❤

sharunkumar · 2025-05-16T18:49:40Z

@colinhacks thanks for the workaround with:

const myEnum = z.enum(["a", "b", "c"], {
  error: (iss): string => `Expected ${Object.values(myEnum.def.entries)}, received ${iss.input}`,
});

is there a way, somehow to apply this globally in v4? with this method it looks like we'd have to assign this param to every enum definition for the intended functionality

colinhacks closed this as completed May 15, 2025

colinhacks mentioned this issue May 15, 2025

v4: z.enum() error does not contain the recieved info #4109

Closed

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