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The data property of a Boom error gets mangled when the error comes from a validator #4582
Description
Runtime
node.js
Runtime version
v24.12.0
Module version
v21.4.9
Last module version without issue
v20.3.0
Used with
hapi application
Any other relevant information
I believe #4350 introduced an edge case issue.
What are you trying to achieve or the steps to reproduce?
Here is a distilled test to showcase the issue.
import Boom from "@hapi/boom"; // 10.0.1
import Hapi from "@hapi/hapi"; // 21.4.9
import Joi from "joi"; // 18.2.3
import assert from "node:assert";
import { afterEach, beforeEach, describe, it } from "node:test";
describe("error mangling showcase", () => {
let server;
const myError = Boom.badRequest("My message", { my: "data" });
beforeEach(async () => {
// Initialize Hapi
server = Hapi.server();
await server.initialize();
// Set up a basic global error response formatter to expose the error's data property
server.ext("onPreResponse", (request, h) => {
const { response } = request;
if (response.isBoom) {
const error = response;
error.output.payload = {
error: {
message: error.message,
data: error.data,
},
};
}
return h.continue;
});
});
afterEach(async () => {
await server.stop();
});
it("throws myError from handler", async () => {
server.route({
method: "GET",
path: "/",
handler: function () {
throw myError;
},
});
const res = await server.inject({
method: "get",
url: "/",
});
// This assertion passes regarless of Hapi version
assert.deepStrictEqual(res.result, {
error: {
message: "My message",
data: { my: "data" },
},
});
});
it("throws myError from validation schema", async () => {
server.route({
method: "GET",
path: "/",
handler: function () {
return "Hello world!";
},
options: {
validate: {
query: Joi.object({
dummy: Joi.required().error(myError),
}),
},
},
});
const res = await server.inject({
method: "get",
url: "/",
});
// This assertion fails on Hapi v21 and onward
assert.deepStrictEqual(res.result, {
error: {
message: "My message",
// the data is { defaultError: myError } starting from Hapi v21
data: { my: "data" },
},
});
});
});What was the result you got?
$ node --test example.mjs
▶ issue showcase
✔ throws myError from handler (23.230669ms)
✖ throws myError from validation schema (11.012993ms)
✖ issue showcase (35.352659ms)
ℹ tests 2
ℹ suites 1
ℹ pass 1
ℹ fail 1
ℹ cancelled 0
ℹ skipped 0
ℹ todo 0
ℹ duration_ms 399.773655
✖ failing tests:
test at example.mjs:62:3
✖ throws myError from validation schema (11.012993ms)
AssertionError [ERR_ASSERTION]: Expected values to be strictly deep-equal:
+ actual - expected
+ <ref *2> {
- {
error: {
+ data: <ref *1> {
+ defaultError: Error: My message
+ at SuiteContext.<anonymous> (file:///[redacted]/example.mjs:10:24)
+ at Suite.runInAsyncScope (node:async_hooks:214:14)
+ at Suite.createBuild (node:internal/test_runner/test:1478:13)
+ at new Suite (node:internal/test_runner/test:1469:28)
+ at Test.createSubtest (node:internal/test_runner/test:865:18)
+ at run (node:internal/test_runner/harness:364:28)
+ at test (node:internal/test_runner/harness:378:12)
+ at file:///[redacted]/example.mjs:8:1
+ at ModuleJob.run (node:internal/modules/esm/module_job:413:25)
+ at async onImport.tracePromise.__proto__ (node:internal/modules/esm/loader:660:26) {
+ data: [Circular *1],
+ isBoom: true,
+ isServer: false,
+ output: {
+ headers: {},
+ payload: [Circular *2],
+ statusCode: 400
+ }
+ }
- data: {
- my: 'data'
},
message: 'My message'
}
}
at TestContext.<anonymous> (file:///[redacted]/example.mjs:83:12)
at process.processTicksAndRejections (node:internal/process/task_queues:103:5)
at async Test.run (node:internal/test_runner/test:1113:7)
at async Suite.processPendingSubtests (node:internal/test_runner/test:788:7) {
generatedMessage: true,
code: 'ERR_ASSERTION',
actual: { error: { message: 'My message', data: [Object] } },
expected: { error: { message: 'My message', data: [Object] } },
operator: 'deepStrictEqual',
diff: 'simple'
}What result did you expect?
$ node --test example.mjs
▶ issue showcase
✔ throws myError from handler (35.244367ms)
✔ throws myError from validation schema (12.917042ms)
✔ issue showcase (50.673704ms)
ℹ tests 2
ℹ suites 1
ℹ pass 2
ℹ fail 0
ℹ cancelled 0
ℹ skipped 0
ℹ todo 0
ℹ duration_ms 718.821985
Activity
kanongil commentedon Jul 10, 2026
It is definitely unfortunate that validation errors get their
dataproperty rewritten.I'm not sure how to fix this though. It seems that adding a
defaultErrorproperty to thedataobject was a mistake in the first place, as neither overwriting, merging, or preserving an existingdataobject seems appropriate. If it was implemented today, I would put it in theerror.causeproperty which is there to expose underlying errors.kanongil commentedon Jul 20, 2026
Hmm, it seems that there is a proper issue here, but it is in Joi. Namely, the error passed to
.error()is returned as-is, meaning that subsequent changes (including setting thedata.defaultErrorproperty) is unintentionally made to that exact object. The general expectation is that you are free to modify a thrown error. As used in hapi, this introduces a concurrency issue, where a readdata.defaultErrorvalue could belong to the wrong error (even when the error has nodata)!The fix for the above will be to return a clone of the error in Joi, and possibly eventually removing support for such static errors given that cloning an error is somewhat problematic.
Incidentally, this whole issue would probably be fixed with my refactor in hapijs/boom#304, which never modifies the passed error.
Marsup commentedon Sep 2, 2026
I'm commenting here as I've been pinged on joi as well. @kanongil's solution is indeed best, but we're not there yet, so in the meantime, I'd advise you to use a factory function with fresh errors like it's already mentioned in the
.error()documentation.