Many users have reported running into the error where MBR2GPT conversion failed cannot find room for the EFI system partition. This issue usually appears during the conversion of a disk from MBR to GPT. Understanding the causeshere and findthe right fix.
The error “MBR2GPT conversion failed: cannot find room” usually appears when you try to convert a disk from MBR (Master Boot Record) to GPT (GUID Partition Table) using Microsoft’s MBR2GPT.exe tool, but the tool cannot locate enough unallocated space in the disk layout to create the required EFI System Partition (ESP).
Here’s a breakdown of what it means:
◉ No free space available: GPT requires an EFI System Partition (about 100 MB or more). If your disk is fully allocated with no unallocated space, MBR2GPT cannot create it.
◉ Partition alignment issues: The existing partitions may leave no suitable area for the ESP, even if there is free space.
◉ Too many primary partitions: MBR supports up to 4 primary partitions. If all 4 are used, the conversion tool cannot rearrange partitions to make space.
◉ Reserved space is blocked: Sometimes, recovery or OEM partitions are in the way, preventing proper placement of the ESP.
The MBR2GPT tool is used to convert a disk from MBR (Master Boot Record) to GPT (GUID Partition Table) without data loss. However, it may fail with the error “cannot find room”, usually because there isn’t enough unallocated space on the disk to create the EFI system partition required by GPT. Here are five effective ways to fix it.
One of the most straightforward ways to create space is to shrink an existing partition. By doing so, you can free up enough unallocated space for the EFI partition.
Step 1. Press Win + X and select Disk Management.
Step 2. Right-click the partition you want to shrink (usually C:).
Step 3. Select Shrink Volume and enter the amount of space to free up (at least 100 MB).
Step 4. Click Shrink, then retry the MBR2GPT conversion.
If shrinking isn’t possible, another option is to remove a non-essential partition. This can provide the required space at the end of the disk.
Step 1. Open Disk Management.
Step 2. Identify any partition that can be safely deleted (like a recovery or data partition).
Step 3. Right-click it and select Delete Volume.
Step 4. Confirm deletion and ensure the space is now Unallocated.
Step 5. Retry the MBR2GPT conversion.
Sometimes the issue occurs because the Master Boot Record itself is damaged or inconsistent. Repairing it first can resolve the problem.
Step 1. Boot from a Windows installation media.
Step 2. Open Command Prompt and type:
bootrec /fixmbr
bootrec /fixboot
bootrec /rebuildbcd
Step 3. Restart the computer and attempt MBR2GPT conversion again.
If all else fails, using reliable third-party partition tools can bypass the limitations of MBR2GPT.
Download and install software like AOMEI Partition Assistant. It’s an all-in-one disk management tool designed to handle complex partitioning tasks with ease. Unlike the built-in MBR2GPT tool, AOMEI Partition Assistant provides a Convert to GPT/MBR Disk feature that works without deleting partitions or losing data.
This makes it a far simpler and safer alternative to MBR2GPT, especially when you encounter errors like insufficient space for creating the EFI partition.
Step 1. Download, install and launch this MBR2GPT alternative. In the main window, right-click the disk you want to convert and select "Convert to GPT".
Step 2. Click "OK" in the pop-up box to confirm the operation. It will prompt us that GPT boots from UEFI mode rather than BIOS.
Step 3. View the virtual result. The disk has changed to GPT disk from MBR and all partitions and data are kept the same. Click "Apply" then "Proceed" to start the pending conversion.
The “MBR2GPT conversion failed cannot find room” error can be intimidating, but it’s not the end of the world. By shrinking partitions, freeing space, or using tools like AOMEI Partition Assistant, you can successfully convert MBR to GPT without data loss. If all else fails, cloning or reinstalling Windows ensures you’re running on the modern GPT partition style required for UEFI and Windows 11.