From 778197246a643c2d0cc7cb61f1fb64fc1c9a22dc Mon Sep 17 00:00:00 2001
From: "copilot-swe-agent[bot]" <198982749+Copilot@users.noreply.github.com>
Date: Fri, 7 Aug 2026 03:00:16 +0000
Subject: [PATCH] Deprecate serializing invalid `Date`s

Co-authored-by: charmander <1889843+charmander@users.noreply.github.com>
---
 packages/pg/lib/utils.js             | 10 ++++++++++
 packages/pg/test/unit/utils-tests.js | 17 +++++++++++++++++
 2 files changed, 27 insertions(+)

diff --git a/packages/pg/lib/utils.js b/packages/pg/lib/utils.js
index 638b43970..4649405a8 100644
--- a/packages/pg/lib/utils.js
+++ b/packages/pg/lib/utils.js
@@ -1,9 +1,16 @@
 'use strict'
 
 const defaults = require('./defaults')
+const nodeUtils = require('util')
 
 const { isDate } = require('util/types')
 
+const invalidDateDeprecationNotice = nodeUtils.deprecate(
+  () => {},
+  'Sending an invalid date to Postgres is deprecated and will throw an error in the next major version of pg. Ensure any Date object passed as a query parameter is valid.',
+  'PG_INVALID_DATE'
+)
+
 function escapeElement(elementRepresentation) {
   const escaped = elementRepresentation.replace(/\\/g, '\\\\').replace(/"/g, '\\"')
 
@@ -54,6 +61,9 @@ const prepareValue = function (val, seen) {
       return Buffer.from(val.buffer, val.byteOffset, val.byteLength)
     }
     if (isDate(val)) {
+      if (isNaN(val.getTime())) {
+        invalidDateDeprecationNotice()
+      }
       if (defaults.parseInputDatesAsUTC) {
         return dateToStringUTC(val)
       } else {
diff --git a/packages/pg/test/unit/utils-tests.js b/packages/pg/test/unit/utils-tests.js
index 5f75f6c2d..edb01f414 100644
--- a/packages/pg/test/unit/utils-tests.js
+++ b/packages/pg/test/unit/utils-tests.js
@@ -89,6 +89,23 @@ test('prepareValues: 1 BC date prepared properly', function () {
   helper.resetTimezoneOffset()
 })
 
+test('prepareValue: invalid date emits deprecation warning', function () {
+  const warningSeen = new Promise((resolve) => {
+    const onWarning = (warning) => {
+      if (warning.code === 'PG_INVALID_DATE') {
+        process.removeListener('warning', onWarning)
+        resolve()
+      }
+    }
+    process.on('warning', onWarning)
+  })
+
+  const out = utils.prepareValue(new Date(NaN))
+  assert.strictEqual(out, '0NaN-NaN-NaNTNaN:NaN:NaN.NaN+NaN:NaN')
+
+  return warningSeen
+})
+
 test('prepareValues: undefined prepared properly', function () {
   const out = utils.prepareValue(void 0)
   assert.strictEqual(out, null)