Fixed: Bad GPT Partition, Invalid Signature

December 12, 2018

Are you confronted with the error “bad GPT partition, invalid signature” showing in TestDisk? Don’t worry! Follow this article to fix it simply.

The error: bad GPT partition, invalid signature

TestDisk is a free data recovery utility. It helps you to recover lost partitions and make non-booting disks bootable again when the symptoms are caused by faulty software, certain types of viruses and human error. It can also be used to repair some filesystem errors.

After you analyze your current partition structure with TestDisk, you can find the exact problem with your disk. “Bad GPT partition, invalid signature” is one of the common problems. Here is a real case:

“I have a GPT partitioned HDD which isn't recognized by Windows. The disk management shows the entire disk as unallocated.

I am 100% sure that the partitions and their file systems are undamaged. TestDisk shows me this:

Bad GPT Partition

It finds the 128MB reserved space and the 2nd partition. Is there any tool (Windows or Linux) that I can use to repair the GPT so that Windows recognizes it again?”

How to fix the error “bad GPT partition, invalid signature” simply?

When you encounter the error “bad GPT partition, invalid signature”, it could mean GPT partition is corrupted or the partition table is invalid. I’ll show you how to fix it in two efficient ways separately:

Solution 1: repair corrupted GPT partition with TestDisk

You can not only check disk/partition errors but also fix them with TestDisk. Follow the steps below to perform GPT partition recovery in Windows 10/8/7 with the help of TestDisk:

1. After the error is reported, confirm at Quick Search to proceed.

2. When all the partitions are found, highlight each partition and use left/right arrow keys to change partition characteristics. Press Enter to continue.

Tips: There are five partition characteristics available: *=Primary bootable, P=Primary, L=Logic, E=Extended, D=Deleted. Use D for the partitions you don’t want to recover.

3. If all partitions are listed right, confirm at Write with Enter and then y and OK. The partitions will be registered in the partition table.

TestDisk

Note: If there are partitions not found in Quick Search, you can go Deeper Search before you write partition structure to disk.

Solution 2: fix invalid partition table via a handy freeware

As you see, TestDisk can only be operated in a DOS window via command-line controls. It is difficult to handle this tool for those less experienced users. Fortunately, there is a handy freeware with user-friendly interface which can help you with GPT recovery. It is AOMEI Partition Assistant Standard.

It supports all Windows PC operating systems like Windows 10/8.1/8/7/Vista/XP. It enables you to manage disks and partitions easily. You are allowed to resize, move, merge and format partitions with just a few clicks. Learn how to fix invalid partition table via AOMEI Partition Assistant below:

Step 1. Download, install and run AOMEI Partition Assistant. Right click the disk with bad GPT partitions and select “Rebuild MBR”.

Rebuild MBR

Step 2. Set the type of MBR in the pop-up window.

Set MBR Type

Step 3. Click “Apply” and then “Proceed” to commit the pending operation.

Proceed

Notes:

  • The operation above can only solve problems caused by damaged MBR code instead of missing bootable file or system file.

  • If you want to convert system disk between MBR and GPT, you may upgrade to AOMEI Partition Assistant Professional.

Conclusion

You can pick TestDisk or AOMEI Partition Assistant to fix the error “bad GPT partition, invalid signature”. AOMEI Partition Assistant is more suitable for users who are not too tech savvy, because it offers GUI operations. Apart from fixing invalid partition table, you are able to change partition type ID and erase SSD before selling with AOMEI Partition Assistant. Don’t hesitate to give it a try!