diff --git a/packages/firestore/src/local/indexeddb_schema.ts b/packages/firestore/src/local/indexeddb_schema.ts
index fa282e6f560..a5c79ef450e 100644
--- a/packages/firestore/src/local/indexeddb_schema.ts
+++ b/packages/firestore/src/local/indexeddb_schema.ts
@@ -33,22 +33,23 @@ import { SimpleDbSchemaConverter, SimpleDbTransaction } from './simple_db';
 
 /**
  * Schema Version for the Web client:
- * 1. Initial version including Mutation Queue, Query Cache, and Remote Document
- *    Cache
- * 2. Used to ensure a targetGlobal object exists and add targetCount to it. No
- *    longer required because migration 3 unconditionally clears it.
- * 3. Dropped and re-created Query Cache to deal with cache corruption related
- *    to limbo resolution. Addresses
- *    https://github.com/firebase/firebase-ios-sdk/issues/1548
- * 4. Multi-Tab Support.
- * 5. Removal of held write acks.
- * 6. Create document global for tracking document cache size.
- * 7. Ensure every cached document has a sentinel row with a sequence number.
- * 8. Add collection-parent index for Collection Group queries.
- * 9. Change RemoteDocumentChanges store to be keyed by readTime rather than
- *    an auto-incrementing ID. This is required for Index-Free queries.
+ * 1.  Initial version including Mutation Queue, Query Cache, and Remote
+ *     Document Cache
+ * 2.  Used to ensure a targetGlobal object exists and add targetCount to it. No
+ *     longer required because migration 3 unconditionally clears it.
+ * 3.  Dropped and re-created Query Cache to deal with cache corruption related
+ *     to limbo resolution. Addresses
+ *     https://github.com/firebase/firebase-ios-sdk/issues/1548
+ * 4.  Multi-Tab Support.
+ * 5.  Removal of held write acks.
+ * 6.  Create document global for tracking document cache size.
+ * 7.  Ensure every cached document has a sentinel row with a sequence number.
+ * 8.  Add collection-parent index for Collection Group queries.
+ * 9.  Change RemoteDocumentChanges store to be keyed by readTime rather than
+ *     an auto-incrementing ID. This is required for Index-Free queries.
+ * 10. Rewrite the canonical IDs to the explicit Protobuf-based format.
  */
-export const SCHEMA_VERSION = 9;
+export const SCHEMA_VERSION = 10;
 
 /** Performs database creation and schema upgrades. */
 export class SchemaConverter implements SimpleDbSchemaConverter {
@@ -71,7 +72,7 @@ export class SchemaConverter implements SimpleDbSchemaConverter {
       fromVersion < toVersion &&
         fromVersion >= 0 &&
         toVersion <= SCHEMA_VERSION,
-      `Unexpected schema upgrade from v${fromVersion} to v{toVersion}.`
+      `Unexpected schema upgrade from v${fromVersion} to v${toVersion}.`
     );
 
     const simpleDbTransaction = new SimpleDbTransaction(txn);
@@ -145,6 +146,10 @@ export class SchemaConverter implements SimpleDbSchemaConverter {
         createRemoteDocumentReadTimeIndex(txn);
       });
     }
+
+    if (fromVersion < 10 && toVersion >= 10) {
+      p = p.next(() => this.rewriteCanonicalIds(simpleDbTransaction));
+    }
     return p;
   }
 
@@ -299,6 +304,17 @@ export class SchemaConverter implements SimpleDbSchemaConverter {
           });
       });
   }
+
+  private rewriteCanonicalIds(
+    txn: SimpleDbTransaction
+  ): PersistencePromise<void> {
+    const targetStore = txn.store<DbTargetKey, DbTarget>(DbTarget.store);
+    return targetStore.iterate((key, originalDbTarget) => {
+      const originalTargetData = this.serializer.fromDbTarget(originalDbTarget);
+      const updatedDbTarget = this.serializer.toDbTarget(originalTargetData);
+      return targetStore.put(updatedDbTarget);
+    });
+  }
 }
 
 function sentinelKey(path: ResourcePath): DbTargetDocumentKey {
@@ -1079,6 +1095,8 @@ export const V8_STORES = [...V6_STORES, DbCollectionParent.store];
 
 // V9 does not change the set of stores.
 
+// V10 does not change the set of stores.
+
 /**
  * The list of all default IndexedDB stores used throughout the SDK. This is
  * used when creating transactions so that access across all stores is done
diff --git a/packages/firestore/test/unit/local/indexeddb_persistence.test.ts b/packages/firestore/test/unit/local/indexeddb_persistence.test.ts
index 04023a85b1a..c73e102c691 100644
--- a/packages/firestore/test/unit/local/indexeddb_persistence.test.ts
+++ b/packages/firestore/test/unit/local/indexeddb_persistence.test.ts
@@ -16,6 +16,7 @@
  */
 
 import { expect } from 'chai';
+import { Query } from '../../../src/core/query';
 import { SnapshotVersion } from '../../../src/core/snapshot_version';
 import { decode, encode } from '../../../src/local/encoded_resource_path';
 import { IndexedDbPersistence } from '../../../src/local/indexeddb_persistence';
@@ -53,12 +54,13 @@ import { LruParams } from '../../../src/local/lru_garbage_collector';
 import { PersistencePromise } from '../../../src/local/persistence_promise';
 import { ClientId } from '../../../src/local/shared_client_state';
 import { SimpleDb, SimpleDbTransaction } from '../../../src/local/simple_db';
+import { TargetData, TargetPurpose } from '../../../src/local/target_data';
 import { PlatformSupport } from '../../../src/platform/platform';
 import { firestoreV1ApiClientInterfaces } from '../../../src/protos/firestore_proto_api';
 import { JsonProtoSerializer } from '../../../src/remote/serializer';
 import { AsyncQueue } from '../../../src/util/async_queue';
 import { FirestoreError } from '../../../src/util/error';
-import { doc, path, version } from '../../util/helpers';
+import { doc, filter, path, version } from '../../util/helpers';
 import { SharedFakeWebStorage, TestPlatform } from '../../util/test_platform';
 import {
   INDEXEDDB_TEST_DATABASE_NAME,
@@ -728,6 +730,44 @@ describe('IndexedDbSchema: createOrUpgradeDb', () => {
     });
   });
 
+  it('rewrites canonical IDs during upgrade from version 9 to 10', async () => {
+    await withDb(9, db => {
+      const sdb = new SimpleDb(db);
+      return sdb.runTransaction('readwrite-idempotent', V8_STORES, txn => {
+        const targetsStore = txn.store<DbTargetKey, DbTarget>(DbTarget.store);
+
+        const filteredQuery = Query.atPath(path('collection')).addFilter(
+          filter('foo', '==', 'bar')
+        );
+        const initialTargetData = new TargetData(
+          filteredQuery.toTarget(),
+          /* targetId= */ 2,
+          TargetPurpose.Listen,
+          /* sequenceNumber= */ 1
+        );
+
+        const serializedData = TEST_SERIALIZER.toDbTarget(initialTargetData);
+        serializedData.canonicalId = 'invalid_canonical_id';
+
+        return targetsStore.put(TEST_SERIALIZER.toDbTarget(initialTargetData));
+      });
+    });
+
+    await withDb(10, db => {
+      const sdb = new SimpleDb(db);
+      return sdb.runTransaction('readwrite-idempotent', V8_STORES, txn => {
+        const targetsStore = txn.store<DbTargetKey, DbTarget>(DbTarget.store);
+        return targetsStore.iterate((key, value) => {
+          const targetData = TEST_SERIALIZER.fromDbTarget(value).target;
+          const expectedCanonicalId = targetData.canonicalId();
+
+          const actualCanonicalId = value.canonicalId;
+          expect(actualCanonicalId).to.equal(expectedCanonicalId);
+        });
+      });
+    });
+  });
+
   it('can use read-time index after schema migration', async () => {
     // This test creates a database with schema version 8 that has a few
     // remote documents, adds an index and then reads new documents back