diff --git a/packages/lib/services/synchronizer/Synchronizer.basics.test.ts b/packages/lib/services/synchronizer/Synchronizer.basics.test.ts
index 044649dfb..33d3544c3 100644
--- a/packages/lib/services/synchronizer/Synchronizer.basics.test.ts
+++ b/packages/lib/services/synchronizer/Synchronizer.basics.test.ts
@@ -8,6 +8,7 @@ import WelcomeUtils from '../../WelcomeUtils';
 import { NoteEntity } from '../database/types';
 import { fetchSyncInfo, setAppMinVersion, uploadSyncInfo } from './syncInfoUtils';
 import { ErrorCode } from '../../errors';
+import { LockType } from './LockHandler';
 
 describe('Synchronizer.basics', () => {
 
@@ -461,6 +462,35 @@ describe('Synchronizer.basics', () => {
 		expect(remotes.find(r => r.path === `${note.id}.md`)).toBeTruthy();
 	}));
 
+	it('should recover from failures to release sync locks', async () => {
+		await synchronizer().start();
+
+		const lockHandler = synchronizer().lockHandler();
+
+		let allowLockRelease = false;
+
+		// Use .spyOn to simulate an error that might, for example, be caused by network
+		// failure.
+		const spy = jest.spyOn(lockHandler, 'releaseLock').mockImplementation(async (type) => {
+			if (type === LockType.Sync && !allowLockRelease) {
+				throw new Error('Testing lock release failure');
+			}
+		});
+
+		let syncError: Error|null = null;
+		try {
+			await synchronizer().start();
+		} catch (error) {
+			syncError = error;
+		}
+		expect(syncError).not.toBeNull();
+		spy.mockClear();
+
+		// Should sync successfully, after failure
+		allowLockRelease = true;
+		await synchronizerStart();
+	});
+
 	it('should throw an error if the app version is not compatible with the sync target info', (async () => {
 		await synchronizerStart();