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Summary :

no free MBR slots

How does the error "No Free MBR Slot" occurs in MiniTool Partition Wizard. If the operation to be made will break the partition number limit of an MBR disk, MiniTool will send out "No Free MBR Slot" message. Learn how to resolve this issue.

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Partition Wizard Reports No Free MBR Slots Error

MiniTool Partition Wizard is a highly competent partitioning toolkit that both average users and experienced users have little difficulty to cope with, and is always a good choice when you're doing hard drive management without killing data. Partition Wizard consists of five kinds of licenses and supports all latest partition technologies such as Windows dynamic disks and GPT disk, as most programs of its industry do.

Although Partition Wizard offers user-friendly interface, many users may get confused when encountering some error prompts, like Error Code 4 and Error Code 40. What we are going to talk today is one of the hot discussions: Partition Wizard reports No Free MBR Slots Error.

MiniTool says there is no free mbr on the disk

Note: In Windows Disk Management, this error is shown as "the operation will convert the selected disk(s) to dynamic disk(s)…" or "the disk already contains the maximum number of partitions" as showing below:

disk already contains maximum partition

the operation you selected will convert the selected basic disk to dynamic disk

This post tells what to do if you can't create partition in Windows 8.

How Does This Happen

Before getting into the main part, we would like to explain the related. In Partition Wizard, No free MBR slots occurs on an MBR disk, which is a phenomenon indicating that the operation you are carrying out will break the rule that there should be four primary partitions or three primary partitions plus one extended partition at most on an MBR disk (extended partition can be further divided into many logical partitions). Thus, Partition Wizard won't go any further.

However, when seeing this error message, you don’t need to get worried, because Partition Wizard also offers several ways to help you out.

"Finally I get the reasons that lead to Partition Wizard error 'no free MBR slots on the disk', which may be helpful for you guys…"Click to tweet

Let's discuss in detail.

How to Remove No Free MBR Slots

Chapter 1: Partition Wizard Can't Create Partition - No Free MBR Slots

It is my hard disk original state:
Local Disk C:450 GB
RECOVERY D:15 GB
But system has 2 others as:
SYSTEM 199 MB
HP_tools 104 MB
I want to create at least 1 other local disk, so I resized (Cto 120 GB and 330GB volume remained as free.
When I clicking on an Unallocated space and click on "create" reply this error:
"Partition Wizard cannot create a partition at here. There are no free MBR slots on the disk."
Now I don't know how to make MBR slots available. --from Tomshardware

While creating a new partition, "No free MBR slot" may emerge in the following two scenarios: 

Scenario 1: There are four primary partitions on the same disk already.

As the screenshot shows below, there are already four primary partitions on an MBR disk, Partition Wizard can't create a new partition and gives out the error message.

cant create partition already four primary partitions

If you require more than four partitions, you need to convert the primary partition followed by unallocated space to logical partition, then use the unallocated space to create another logical partition. In this way both logical partitions are contained in an extended partition, forming the partition layout of three primary partitions plus one extended partition.

Step 1: Click on the primary partition to be converted (in our case, it's H:) and employ "Set Partition as Logical" from the Operation menu. Then click "Apply" at the toolbar to finish this conversion.

convert one primary partition near the unallocated to logical

Step 2: After conversion, you can normally employ "Create Partition" feature on the unallocated space. In the pop-up window, you can specify the parameters including partition label, drive letter, file system, cluster size and partition size of the new partition. Remember to tick "Apply" in the end.

create a new partition now

How to create a logical partition in Windows 7?

Useful tips after you create a new partition:

Scenario 2: There are three primary partitions plus one logical partition, but the unallocated space is far away from the logical partition.

Another case is that if there are already three primary partitions plus one logical partition on the hard drive, and the unallocated space is not adjacent with the logical partition, Partition Wizard won't allow creating a partition and reports "No free MBR slots". (Screenshot attached)

cant create partition already four primary partitions and a logical partition

To resolve this problem, you need to convert a primary partition to logical before creating a new partition with the unallocated space.

Note: In this scenario, the primary partition to be converted to logical should be either partition that is adjacent to the logical partition, because extended partition should be included together.

Step 1: Click on the primary partition to be converted (in our case, it's G: or H:, and we choose H:) and select "Set Partition as Logical". Click "Apply" to finish this conversion.

convert the partition between the logical and the unallcated to logical partition

Step 2: After conversion, you can successfully create a new partition with the unallocated space.

create new partition

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For a more intuitive tutorial, you can refer to this video:

"The text interpretation as well as the video show how to escape 'no free MBR slots' in Partition Wizard.We can have a try."Click to tweet

Chapter 2: Partition Wizard Can't Split Partition -No Free MBR Slots

Apart from creating partition, another situation that "No free MBR slot" may appear in Partition Wizard is during the process of splitting partition. Let's see a real life example:

Hello,
Problem: splitting one big partition in two smaller ones fails When I try to split my 95GB partition into two smaller parts, minitool's partition wizard tells there are no free mbr slots, I have no idea how to get free mbr slot.
But the last time I use partition wizard it did help me split one another partition.
Can anybody help me get across this? Or I have other choice? Thanks!

While splitting a new partition, "No free MBR slot" may emerge in the following two scenarios: 

Scenario 1: There are already four primary partitions on the same drive.

If there are already four primary partitions on the same drive, Partition Wizard can't split partition. Because if one of them is split into two parts, there would be five primary partitions or four primary partitions plus one extended partition on an MBR disk - not allowed. (Screenshot attached):

cant split partition already four primary partitions

If no empty slot in MBR partition table occurs in Partition Wizard while you are trying to split one of the four primary partitions, the way to overcome this is to convert the primary partition you would like to split to logical partition at first and then carry out partition division. Take splitting partition H: for example.

Step 1: Right click on partition H:and select "Set Partition as Logical" from Operation menu. Then press "Apply".

convert the partition to be split to logical

Step 2: Now the target partition is shown as logical partition. Click on it and choose "Split Partition" from Operation menu. Then drag the slide button to set the partition sizes of the original partition as well as the new partition before you click "Apply".

split partition now

Scenario 2: When there are three primary partitions plus one logical partition on a hard drive, Partition Wizard can't split primary partitions except the one closely located in front of the logical partition.

cant split primary partition after logical partition

The reason?

By default, when splitting a primary partition, MiniTool Partition Wizard will divide it into two parts: the former part keeps primary, and the latter part turns to logical. However, while splitting a logical partition, both parts are kept as logical. Thus, if there are already three primary partitions plus one extended partition, splitting a primary partition closely located in front of the logical partition can put the logical partitions together, but splitting the rest primary partitions will leave the logical partitions apart from each other, that is to say, there will be more than one extended partition - not allowed.

To make it clearer, we draw a table to show the words.

Disk Layout Primary Logical Primary Primary
Divisible YES YES NO NO
Disk Layout Primary Primary Logical Primary
Divisible NO YES YES NO
Disk Layout Primary Primary Primary Logical
Divisible NO NO YES YES

In this case, you need to select either primary partition adjacent to the logical partition and set it as logical partition before splitting. Take splitting partition H: for example.

Step 1: Click on the primary partition(in our case, it's H:) to be converted and select "Set Partition as Logical" from the Operation menu. Then click "Apply" to execute this change.

convert the primary partition to logical to create a whole extended partition

Step 2: Now click partition H: and select "Split Partition" from the menu. After confirming the partition sizes of the original partition and the new partition, you can press "Apply" to end the operation.

split partition allowed

Note:
  1. Please do not set a system partition as logical, for this operation may cause your system unbootable.
  2. To split a partition, the minimum partition size should be no smaller than 200MB, otherwise you will receive another error message: Not Enough Free Space.

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Chapter 3: How to Avoid No Free MBR Slots Error

Now you know how to solve this MiniTool Partition Wizard error. In fact there is another way that can solve this error once for all, that is to convert MBR disk to GPT disk. The reason of doing this is that in GPT disk differs from MBR disk in many aspects:

  • In Windows, all GPT partitions are treated as primary partitions.
  • In Windows, the maximum partition number of GPT disk reaches up to 128 - a rather large number for you to partition a hard drive without worrying about "no empty slot in MBR partition table".
  • GPT can recognize disks larger than 2TB, while the upper limit for MBR is 2TB.
  • The GUID partition table is automatically backed up to resist virus infection or misoperation, which is a deficiency for MBR.

Please take care that the Free Edition is able to convert non-system disk form MBR to GPT. To deal with the system disk, use MiniTool Partition Wizard Bootable instead, in case that any accident may lead to the operating system fails to boot. Step-by-step guide is showing below:

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Step 1: Right click on the disk icon of the drive to be converted, and select "Convert MBR Disk to GPT Disk" from the pop-up window.

Step 2: You can preview this drive will be converted to GPT disk. Click "Apply" to save this change.

convert MBR disk to GPT

The Advantages of Using Partition Wizard

After saying so much on the topic "no empty slot in MBR partition table", you must have mastered the causes and the solutions. Now let's look away and focus on another point: since Partition Wizard gives the similar error message with Disk Management while creating partition, what is the advantage of using this freeware, does Free means Futile?

If you are a fresh user of MiniTool Partition Wizard, you may have no idea of the power of this free partition magic. Compared with Disk Management, Partition Wizard (free edition) not only gets rid of the limitation that extend volumegreyed out, but also wins out in these features:

  • Create FAT32 partition larger than 32 GB.
  • Directly split one partition into two parts.
  • Move partition location.
  • Convert FAT to NTFS and vice versa without formatting.
  • Convert MBR to GPT and vice versa without deleting any volume.
  • Migrate operating system to another drive to back up system.
  • Copy the whole disk for hard drive backup or upgrading.
  • Recover lost/deleted partition.
  • More for you to discover…

See! This free partition magic is not only free, but also powerful, and has earned great reputation all around the world. Besides, the free edition of Partition Wizard can be applied on all packages of Windows XP/Vista/7/8/10. In addition, if you use the paid versions, you can easily merge partition, change cluster size, manage dynamic disk on Windows PC or Windows Server. The concise interface and concrete instructions will lead you through all operations without effort.

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Bottom Line

In this post, we mainly discuss why MiniTool Partition Wizard can't create/split partition, responding a "No free MBR slots" error, along with the solutions. If you are suffering this obsession, just try these solutions.

Besides, Partition Wizard is really helpful in dealing with all kinds of disk partition management issues. If you are considering doing things in this aspect, just download the free version to have a try. For more questions or suggestions please leave us comments below or directly contact [email protected]. Thanks in advance.

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