diff --git a/spec/schemas.spec.js b/spec/schemas.spec.js
index 5d92ef36e1..f9f29c733e 100644
--- a/spec/schemas.spec.js
+++ b/spec/schemas.spec.js
@@ -3842,6 +3842,7 @@ describe('schemas', () => {
     });
 
     it_id('cbd5d897-b938-43a4-8f5a-5d02dd2be9be')(it_exclude_dbs(['postgres']))('cannot update to duplicate value on unique index', done => {
+      loggerErrorSpy.calls.reset();
       const index = {
         code: 1,
       };
@@ -3868,6 +3869,12 @@ describe('schemas', () => {
         .then(done.fail)
         .catch(error => {
           expect(error.code).toEqual(Parse.Error.DUPLICATE_VALUE);
+          // Client should only see generic message (no schema info exposed)
+          expect(error.message).toEqual('A duplicate value for a field with unique values was provided');
+          // Server logs should contain full MongoDB error message with detailed information
+          expect(loggerErrorSpy).toHaveBeenCalledWith('Duplicate key error:', jasmine.stringContaining('E11000 duplicate key error'));
+          expect(loggerErrorSpy).toHaveBeenCalledWith('Duplicate key error:', jasmine.stringContaining('test_UniqueIndexClass'));
+          expect(loggerErrorSpy).toHaveBeenCalledWith('Duplicate key error:', jasmine.stringContaining('code_1'));
           done();
         });
     });
diff --git a/src/Adapters/Storage/Mongo/MongoStorageAdapter.js b/src/Adapters/Storage/Mongo/MongoStorageAdapter.js
index 50fd348861..24b206aec9 100644
--- a/src/Adapters/Storage/Mongo/MongoStorageAdapter.js
+++ b/src/Adapters/Storage/Mongo/MongoStorageAdapter.js
@@ -519,7 +519,7 @@ export class MongoStorageAdapter implements StorageAdapter {
       .then(() => ({ ops: [mongoObject] }))
       .catch(error => {
         if (error.code === 11000) {
-          // Duplicate value
+          logger.error('Duplicate key error:', error.message);
           const err = new Parse.Error(
             Parse.Error.DUPLICATE_VALUE,
             'A duplicate value for a field with unique values was provided'
@@ -605,6 +605,7 @@ export class MongoStorageAdapter implements StorageAdapter {
       .then(result => mongoObjectToParseObject(className, result, schema))
       .catch(error => {
         if (error.code === 11000) {
+          logger.error('Duplicate key error:', error.message);
           throw new Parse.Error(
             Parse.Error.DUPLICATE_VALUE,
             'A duplicate value for a field with unique values was provided'