By Lucas / Last Updated June 23, 2021

There are no free MBR slots on the disk error

Some users of Partition Wizard report that they received the “No free MBR slot” or “There are no free MBR slots on the disk” when they try to create a partition with unallocated space of selected disk in Windows 10. The error occurs on MBR disk usually and also happens when splitting or extending the specified partition. What’s wrong?

According to the FAQ of Partition Wizard, there are two scenarios may cause such error. Firstly, there are already four primary partitions on the disk. Secondly, there are three primary partitions and one or more logical partitions on the disk. Therein, the unallocated space that used to create a partition does not adjacent to the logical drive. That is to say, it cannot be created as a Logical drive. However, based on the primary partition limit of MBR, it cannot be created as Primary partition as well. Thus, error emerges.

The solution provided by Partition Wizard for both situations is to change primary partition to logical with the feature of “Set partition as logical”. However, except for that solution, you can try other attempts.

Fix No free MBR slots in two effectively ways

When fails to create partition with Partition Wizard, it is not a bad choice to choose other workarounds to achieve the goal. Two simple methods to solve no free MBR slot error will be introduced in following parts. Take the one that is suitable for you.

Assign a drive in Windows Disk Management

1. Press Win + R to start Run. Type diskmgmt.msc and press Enter, and run as administrator.

2. In Disk Management, right click the unallocated space and select New Simple Volume.

New Simple Volume

3. Follow the wizard to complete the creating.

Specify Volume Size

It is simple and fast. However, you may get this prompting message “You cannot create a new volume in this unallocated space because the disk already contains the maximum number of partitions” if there are already four primary partitions on the disk. As a result, you need to turn to another way to settle no empty slot in MBR table issue.

Fix “there are no MBR slots” by converting GPT without data loss

Many users want to keep all partition on the selected disk as primary partitions due to various reasons. Under such circumstances, it is a wise move to convert disk to GPT to break the limitation of MBR. AOMEI Partition Assistant Professional allows you to convert MBR to GPT disk without formatting, whether you want to convert the system disk or the data disk. Please make sure your computer support UEFI boot if you’d like to convert system disk. Then, let’s see how to solve “there are no free MBR slots on the disk” in Windows 10 in simple three steps.

1. Install and run AOMEI Partition Assistant on your computer. Find the disk you encountered “No free MBR slots” and right click it. Select Convert to GPT Disk.

Convert to GPT Disk without data loss

2. Confirm the operation and take a note on the provided information.

Confirm the operation

3. Click Apply on the toolbar and then Proceed to execute the pending operations.

Apply and Proceed



You can fix “There are no free MBR slots on the disk” error with three ways in total, convert primary to logical, assign drive in Disk Management and convert GPT to break the limit. As a matter of fact, AOMEI Partition Assistant is able to create partition, extend partition, shrink partition and split partition for you. More advanced operations like make bootable media, SSD secure erase, migrate Windows 10 to SSD, etc. is supported by the software.