Error Code 4120: Failed to Adjust Partition Size

Solution to invalid parameter or information code 4120 occurring when you clone from a large drive to a smaller drive with AOMEI Backupper.

By Lily Updated on November 13, 2025

Table of Contents

Introduction
Solutions

This article applies to: AOMEI Backupper all versions.

Introduction

Sometimes, when you clone from a large drive to a smaller drive, you may encounter error code 4120:

Clone is initializing...

Checking volumes...

System cloning...

Information Code: 4120

Failed to adjust partition size.

Solutions

Method 1: Delete all partitions on target drive and clone again

Press Windows + X and select Disk Management. Right-click on each partition on the target drive and select Delete Volume.

After the target drive shows unallocated space, open AOMEI Backupper and try disk clone again.

Method 2: Edit the partition size manually

Before starting clone, click Edit Partitions > Manually adjust partition size to edit the size of each partition manually.

If there is still any problem, please feel free to contact us.

Lily · Editor

Lily Green joined AOMEI in 2018 and has since become a professional in the areas of data protection and data transfer. She is committed to helping users protect their precious computer data and troubleshoot Windows system errors. She consistently stays vigilant about the latest trends in technology, guaranteeing that the given information aligned with the ongoing advancements in the field.