diff --git a/.changeset/metal-paws-joke.md b/.changeset/metal-paws-joke.md
new file mode 100644
index 00000000000..fe06475f2cc
--- /dev/null
+++ b/.changeset/metal-paws-joke.md
@@ -0,0 +1,5 @@
+---
+'@firebase/firestore': minor
+---
+
+Updated an outdated error message to include '!=' and 'not-in' as an inequalities.
diff --git a/packages/firestore/src/lite/query.ts b/packages/firestore/src/lite/query.ts
index b148b5a942e..3063e52b8f4 100644
--- a/packages/firestore/src/lite/query.ts
+++ b/packages/firestore/src/lite/query.ts
@@ -795,7 +795,7 @@ function validateNewFilter(query: InternalQuery, filter: Filter): void {
       throw new FirestoreError(
         Code.INVALID_ARGUMENT,
         'Invalid query. All where filters with an inequality' +
-          ' (<, <=, >, or >=) must be on the same field. But you have' +
+          ' (<, <=, !=, not-in, >, or >=) must be on the same field. But you have' +
           ` inequality filters on '${existingField.toString()}'` +
           ` and '${filter.field.toString()}'`
       );
@@ -845,7 +845,7 @@ function validateOrderByAndInequalityMatch(
     throw new FirestoreError(
       Code.INVALID_ARGUMENT,
       `Invalid query. You have a where filter with an inequality ` +
-        `(<, <=, >, or >=) on field '${inequality.toString()}' ` +
+        `(<, <=, !=, not-in, >, or >=) on field '${inequality.toString()}' ` +
         `and so you must also use '${inequality.toString()}' ` +
         `as your first argument to orderBy(), but your first orderBy() ` +
         `is on field '${orderBy.toString()}' instead.`
diff --git a/packages/firestore/test/integration/api/validation.test.ts b/packages/firestore/test/integration/api/validation.test.ts
index dc1102432e4..ec56d625bee 100644
--- a/packages/firestore/test/integration/api/validation.test.ts
+++ b/packages/firestore/test/integration/api/validation.test.ts
@@ -797,7 +797,7 @@ apiDescribe('Validation:', (persistence: boolean) => {
         collection.where('x', '>=', 32).where('y', '<', 'cat')
       ).to.throw(
         'Invalid query. All where filters with an ' +
-          'inequality (<, <=, >, or >=) must be on the same field.' +
+          'inequality (<, <=, !=, not-in, >, or >=) must be on the same field.' +
           ` But you have inequality filters on 'x' and 'y'`
       );
     });
@@ -818,7 +818,7 @@ apiDescribe('Validation:', (persistence: boolean) => {
           collection.where('y', '>', 32).where('x', '!=', 33)
         ).to.throw(
           'Invalid query. All where filters with an ' +
-            'inequality (<, <=, >, or >=) must be on the same field.' +
+            'inequality (<, <=, !=, not-in, >, or >=) must be on the same field.' +
             ` But you have inequality filters on 'y' and 'x`
         );
       }
@@ -833,7 +833,7 @@ apiDescribe('Validation:', (persistence: boolean) => {
           collection.where('y', '>', 32).where('x', 'not-in', [33])
         ).to.throw(
           'Invalid query. All where filters with an ' +
-            'inequality (<, <=, >, or >=) must be on the same field.' +
+            'inequality (<, <=, !=, not-in, >, or >=) must be on the same field.' +
             ` But you have inequality filters on 'y' and 'x`
         );
       }
@@ -846,7 +846,7 @@ apiDescribe('Validation:', (persistence: boolean) => {
         const collection = db.collection('test');
         const reason =
           `Invalid query. You have a where filter with an ` +
-          `inequality (<, <=, >, or >=) on field 'x' and so you must also ` +
+          `inequality (<, <=, !=, not-in, >, or >=) on field 'x' and so you must also ` +
           `use 'x' as your first argument to Query.orderBy(), but your first ` +
           `orderBy() is on field 'y' instead.`;
         expect(() => collection.where('x', '>', 32).orderBy('y')).to.throw(