From a2f9ec42d523a5955a9ec30d7589925fc0c88d0b Mon Sep 17 00:00:00 2001
From: Denver Coneybeare <dconeybe@google.com>
Date: Thu, 27 Mar 2025 03:01:07 +0000
Subject: [PATCH 1/2] fix `undefined` document snapshot data after "clear site
 data"

---
 .changeset/slow-students-fry.md           |  6 +++++
 packages/firestore/src/local/simple_db.ts | 29 +++++++++++++++++++++++
 2 files changed, 35 insertions(+)
 create mode 100644 .changeset/slow-students-fry.md

diff --git a/.changeset/slow-students-fry.md b/.changeset/slow-students-fry.md
new file mode 100644
index 00000000000..45f3cf7e576
--- /dev/null
+++ b/.changeset/slow-students-fry.md
@@ -0,0 +1,6 @@
+---
+'@firebase/firestore': patch
+'firebase': patch
+---
+
+Fix issue where Firestore would produce `undefined` for document snapshot data if using IndexedDB persistence and "clear site data" (or equivalent) button was pressed in the web browser.
diff --git a/packages/firestore/src/local/simple_db.ts b/packages/firestore/src/local/simple_db.ts
index 8665136a9f5..ffe8e534f72 100644
--- a/packages/firestore/src/local/simple_db.ts
+++ b/packages/firestore/src/local/simple_db.ts
@@ -158,6 +158,7 @@ export class SimpleDbTransaction {
  */
 export class SimpleDb {
   private db?: IDBDatabase;
+  private lastDbVersion: number | null = null;
   private versionchangelistener?: (event: IDBVersionChangeEvent) => void;
 
   /** Deletes the specified database. */
@@ -344,6 +345,24 @@ export class SimpleDb {
             event.oldVersion
           );
           const db = (event.target as IDBOpenDBRequest).result;
+          if (
+            this.lastDbVersion !== null &&
+            this.lastDbVersion !== event.oldVersion
+          ) {
+            // This thrown error will get passed to the `onerror` callback
+            // registered above, and will then be propagated correctly.
+            throw new Error(
+              `refusing to open IndexedDB database due to potential ` +
+                `corruption of the IndexedDB database data; this corruption ` +
+                `could be caused by clicking the "clear site data" button in ` +
+                `a web browser; try reloading the web page to re-initialize ` +
+                `the IndexedDB database: ` +
+                `lastDbVersion=${this.lastDbVersion}, ` +
+                `event.oldVersion=${event.oldVersion}, ` +
+                `event.newVersion=${event.newVersion}, ` +
+                `db.version=${db.version}`
+            );
+          }
           this.schemaConverter
             .createOrUpgrade(
               db,
@@ -359,11 +378,21 @@ export class SimpleDb {
             });
         };
       });
+
+      this.db.addEventListener(
+        'close',
+        event => {
+          const db = event.target as IDBDatabase;
+          this.lastDbVersion = db.version;
+        },
+        { passive: true }
+      );
     }
 
     if (this.versionchangelistener) {
       this.db.onversionchange = event => this.versionchangelistener!(event);
     }
+
     return this.db;
   }
 

From a4cb73497acaa7f574896452b9434bdae26e86d4 Mon Sep 17 00:00:00 2001
From: Denver Coneybeare <dconeybe@google.com>
Date: Thu, 27 Mar 2025 16:21:43 +0000
Subject: [PATCH 2/2] simple_db.ts: rename `lastDbVersion` to
 `lastClosedDbVersion` so that its name is more self-documenting

---
 packages/firestore/src/local/simple_db.ts | 10 +++++-----
 1 file changed, 5 insertions(+), 5 deletions(-)

diff --git a/packages/firestore/src/local/simple_db.ts b/packages/firestore/src/local/simple_db.ts
index ffe8e534f72..3327f66acb7 100644
--- a/packages/firestore/src/local/simple_db.ts
+++ b/packages/firestore/src/local/simple_db.ts
@@ -158,7 +158,7 @@ export class SimpleDbTransaction {
  */
 export class SimpleDb {
   private db?: IDBDatabase;
-  private lastDbVersion: number | null = null;
+  private lastClosedDbVersion: number | null = null;
   private versionchangelistener?: (event: IDBVersionChangeEvent) => void;
 
   /** Deletes the specified database. */
@@ -346,8 +346,8 @@ export class SimpleDb {
           );
           const db = (event.target as IDBOpenDBRequest).result;
           if (
-            this.lastDbVersion !== null &&
-            this.lastDbVersion !== event.oldVersion
+            this.lastClosedDbVersion !== null &&
+            this.lastClosedDbVersion !== event.oldVersion
           ) {
             // This thrown error will get passed to the `onerror` callback
             // registered above, and will then be propagated correctly.
@@ -357,7 +357,7 @@ export class SimpleDb {
                 `could be caused by clicking the "clear site data" button in ` +
                 `a web browser; try reloading the web page to re-initialize ` +
                 `the IndexedDB database: ` +
-                `lastDbVersion=${this.lastDbVersion}, ` +
+                `lastClosedDbVersion=${this.lastClosedDbVersion}, ` +
                 `event.oldVersion=${event.oldVersion}, ` +
                 `event.newVersion=${event.newVersion}, ` +
                 `db.version=${db.version}`
@@ -383,7 +383,7 @@ export class SimpleDb {
         'close',
         event => {
           const db = event.target as IDBDatabase;
-          this.lastDbVersion = db.version;
+          this.lastClosedDbVersion = db.version;
         },
         { passive: true }
       );