By Lucas / Last Updated March 4, 2022

About '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 the MBR disk usually and also happens when splitting or extending the specified partition. 

There are no free MBR slots on the disk

According to the FAQ of Partition Wizard, two scenarios may cause this error:

▶ 1. There are already four primary partitions on the disk.
▶ 2. There are three primary partitions and one or more logical partitions on the disk. Therein, the unallocated space that is 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 a Primary partition as well. Thus, error emerges.

The solution provided by Partition Wizard for both situations is to change the 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 a 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 the following parts. Take the one that is suitable for you.

1. 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 the MBR table issue.

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

Many users want to keep all partitions on the selected disk as primary partitions due to various reasons. Under such circumstances, it is a wise move to convert the 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 supports UEFI boot if you’d like to convert the 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.

Download Pro Demo Win 11/10/8.1/8/7/XP
Secure Download

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

2. In the pop-up windows, click "OK" to continue.

OK

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

Apply

Tips:
1. Switch the firmware to boot to UEFI mode after conversion if you convert the system disk to GPT.
2. You can convert the Primary partition to Logical with AOMEI Partition Assistant as well.

Conclusion

You can fix the “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. AOMEI Partition Assistant can create a partition, extend partition, shrink partition and split partition for you. More advanced operations like making Windows to go USB, SSD secure erase, migrating Windows 10 to SSD, etc. are supported by the software.