@@ -79,7 +79,53 @@ function getObjectId(object) {
     return name;
 }
 
+/**
+ * Wraps a config error with details about where the error occurred.
+ * @param {Error} error The original error.
+ * @param {number} originalLength The original length of the config array.
+ * @param {number} baseLength The length of the base config.
+ * @returns {TypeError} The new error with details.
+ */
+function wrapConfigErrorWithDetails(error, originalLength, baseLength) {
+
+    let location = "user-defined";
+    let configIndex = error.index;
+
+    /*
+     * A config array is set up in this order:
+     * 1. Base config
+     * 2. Original configs
+     * 3. User-defined configs
+     * 4. CLI-defined configs
+     *
+     * So we need to adjust the index to account for the base config.
+     *
+     * - If the index is less than the base length, it's in the base config
+     *   (as specified by `baseConfig` argument to `FlatConfigArray` constructor).
+     * - If the index is greater than the base length but less than the original
+     *   length + base length, it's in the original config. The original config
+     *   is passed to the `FlatConfigArray` constructor as the first argument.
+     * - Otherwise, it's in the user-defined config, which is loaded from the
+     *   config file and merged with any command-line options.
+     */
+    if (error.index < baseLength) {
+        location = "base";
+    } else if (error.index < originalLength + baseLength) {
+        location = "original";
+        configIndex = error.index - baseLength;
+    } else {
+        configIndex = error.index - originalLength - baseLength;
+    }
+
+    return new TypeError(
+        `${error.message.slice(0, -1)} at ${location} index ${configIndex}.`,
+        { cause: error }
+    );
+}
+
 const originalBaseConfig = Symbol("originalBaseConfig");
+const originalLength = Symbol("originalLength");
+const baseLength = Symbol("baseLength");
 
 //-----------------------------------------------------------------------------
 // Exports
@@ -106,12 +152,24 @@ class FlatConfigArray extends ConfigArray {
             schema: flatConfigSchema
         });
 
+        /**
+         * The original length of the array before any modifications.
+         * @type {number}
+         */
+        this[originalLength] = this.length;
+
         if (baseConfig[Symbol.iterator]) {
             this.unshift(...baseConfig);
         } else {
             this.unshift(baseConfig);
         }
 
+        /**
+         * The length of the array after applying the base config.
+         * @type {number}
+         */
+        this[baseLength] = this.length - this[originalLength];
+
         /**
          * The base config used to build the config array.
          * @type {Array<FlatConfig>}
@@ -129,6 +187,49 @@ class FlatConfigArray extends ConfigArray {
         Object.defineProperty(this, "shouldIgnore", { writable: false });
     }
 
+    /**
+     * Normalizes the array by calling the superclass method and catching/rethrowing
+     * any ConfigError exceptions with additional details.
+     * @param {any} [context] The context to use to normalize the array.
+     * @returns {Promise<FlatConfigArray>} A promise that resolves when the array is normalized.
+     */
+    normalize(context) {
+        return super.normalize(context)
+            .catch(error => {
+                if (error.name === "ConfigError") {
+                    throw wrapConfigErrorWithDetails(error, this[originalLength], this[baseLength]);
+                }
+
+                throw error;
+
+            });
+    }
+
+    /**
+     * Normalizes the array by calling the superclass method and catching/rethrowing
+     * any ConfigError exceptions with additional details.
+     * @param {any} [context] The context to use to normalize the array.
+     * @returns {FlatConfigArray} The current instance.
+     * @throws {TypeError} If the config is invalid.
+     */
+    normalizeSync(context) {
+
+        try {
+
+            return super.normalizeSync(context);
+
+        } catch (error) {
+
+            if (error.name === "ConfigError") {
+                throw wrapConfigErrorWithDetails(error, this[originalLength], this[baseLength]);
+            }
+
+            throw error;
+
+        }
+
+    }
+
     /* eslint-disable class-methods-use-this -- Desired as instance method */
     /**
      * Replaces a config with another config to allow us to put strings
 
@@ -70,7 +70,7 @@
     "@eslint-community/regexpp": "^4.6.1",
     "@eslint/eslintrc": "^3.0.2",
     "@eslint/js": "9.0.0",
-    "@humanwhocodes/config-array": "^0.12.3",
+    "@humanwhocodes/config-array": "^0.13.0",
     "@humanwhocodes/module-importer": "^1.0.1",
     "@humanwhocodes/retry": "^0.2.3",
     "@nodelib/fs.walk": "^1.2.8",
 
@@ -191,9 +191,9 @@ async function assertMergedResult(values, result) {
 async function assertInvalidConfig(values, message) {
     const configs = createFlatConfigArray(values);
 
-    await configs.normalize();
 
     assert.throws(() => {
+        configs.normalizeSync();
         configs.getConfig("foo.js");
     }, message);
 }
@@ -719,14 +719,162 @@ describe("FlatConfigArray", () => {
     describe("Config array elements", () => {
         it("should error on 'eslint:recommended' string config", async () => {
 
-            await assertInvalidConfig(["eslint:recommended"], "All arguments must be objects.");
+            await assertInvalidConfig(["eslint:recommended"], "Config (unnamed): Unexpected non-object config at original index 0.");
         });
 
         it("should error on 'eslint:all' string config", async () => {
 
-            await assertInvalidConfig(["eslint:all"], "All arguments must be objects.");
+            await assertInvalidConfig(["eslint:all"], "Config (unnamed): Unexpected non-object config at original index 0.");
+        });
+
+
+        it("should throw an error when undefined original config is normalized", () => {
+
+            const configs = new FlatConfigArray([void 0]);
+
+            assert.throws(() => {
+                configs.normalizeSync();
+            }, "Config (unnamed): Unexpected undefined config at original index 0.");
+
+        });
+
+        it("should throw an error when undefined original config is normalized asynchronously", async () => {
+
+            const configs = new FlatConfigArray([void 0]);
+
+            try {
+                await configs.normalize();
+                assert.fail("Error not thrown");
+            } catch (error) {
+                assert.strictEqual(error.message, "Config (unnamed): Unexpected undefined config at original index 0.");
+            }
+
+        });
+
+        it("should throw an error when null original config is normalized", () => {
+
+            const configs = new FlatConfigArray([null]);
+
+            assert.throws(() => {
+                configs.normalizeSync();
+            }, "Config (unnamed): Unexpected null config at original index 0.");
+
+        });
+
+        it("should throw an error when null original config is normalized asynchronously", async () => {
+
+            const configs = new FlatConfigArray([null]);
+
+            try {
+                await configs.normalize();
+                assert.fail("Error not thrown");
+            } catch (error) {
+                assert.strictEqual(error.message, "Config (unnamed): Unexpected null config at original index 0.");
+            }
+
+        });
+
+        it("should throw an error when undefined base config is normalized", () => {
+
+            const configs = new FlatConfigArray([], { baseConfig: [void 0] });
+
+            assert.throws(() => {
+                configs.normalizeSync();
+            }, "Config (unnamed): Unexpected undefined config at base index 0.");
+
+        });
+
+        it("should throw an error when undefined base config is normalized asynchronously", async () => {
+
+            const configs = new FlatConfigArray([], { baseConfig: [void 0] });
+
+            try {
+                await configs.normalize();
+                assert.fail("Error not thrown");
+            } catch (error) {
+                assert.strictEqual(error.message, "Config (unnamed): Unexpected undefined config at base index 0.");
+            }
+
+        });
+
+        it("should throw an error when null base config is normalized", () => {
+
+            const configs = new FlatConfigArray([], { baseConfig: [null] });
+
+            assert.throws(() => {
+                configs.normalizeSync();
+            }, "Config (unnamed): Unexpected null config at base index 0.");
+
+        });
+
+        it("should throw an error when null base config is normalized asynchronously", async () => {
+
+            const configs = new FlatConfigArray([], { baseConfig: [null] });
+
+            try {
+                await configs.normalize();
+                assert.fail("Error not thrown");
+            } catch (error) {
+                assert.strictEqual(error.message, "Config (unnamed): Unexpected null config at base index 0.");
+            }
+
         });
 
+        it("should throw an error when undefined user-defined config is normalized", () => {
+
+            const configs = new FlatConfigArray([]);
+
+            configs.push(void 0);
+
+            assert.throws(() => {
+                configs.normalizeSync();
+            }, "Config (unnamed): Unexpected undefined config at user-defined index 0.");
+
+        });
+
+        it("should throw an error when undefined user-defined config is normalized asynchronously", async () => {
+
+            const configs = new FlatConfigArray([]);
+
+            configs.push(void 0);
+
+            try {
+                await configs.normalize();
+                assert.fail("Error not thrown");
+            } catch (error) {
+                assert.strictEqual(error.message, "Config (unnamed): Unexpected undefined config at user-defined index 0.");
+            }
+
+        });
+
+        it("should throw an error when null user-defined config is normalized", () => {
+
+            const configs = new FlatConfigArray([]);
+
+            configs.push(null);
+
+            assert.throws(() => {
+                configs.normalizeSync();
+            }, "Config (unnamed): Unexpected null config at user-defined index 0.");
+
+        });
+
+        it("should throw an error when null user-defined config is normalized asynchronously", async () => {
+
+            const configs = new FlatConfigArray([]);
+
+            configs.push(null);
+
+            try {
+                await configs.normalize();
+                assert.fail("Error not thrown");
+            } catch (error) {
+                assert.strictEqual(error.message, "Config (unnamed): Unexpected null config at user-defined index 0.");
+            }
+
+        });
+
+
     });
 
     describe("Config Properties", () => {