Looks like no one’s replied in a while. To start the conversation again, simply ask a new question.

I can't boot into my windows after resizing my partition

I'm running OS X 10.10.3 & Windows 7 Home Premium x64

iMac 27 Inch Late 2012 model


I need more space on my windows partition so i decreased the size of my mac partition from 800gb to 675. After this was done i was going to boot into my windows partition and expand it using minitool wizard. I tried this once before and it worked fine but this time my windows partition disappeared once i decreased the size of my mac partition. I did this without backing up any of my windows files and i now i'm worried they might be lost. I tried to fix it using this information i found in this threadI can't boot to Windows after resizing my Mac partition.

I tried some commands in terminal and now the windows partition shows up once i re boot and use the option key but it says the operating system is missing. I had some really important files on my windows partition and i might not be able to replace them. Is there any way i can i get it back to normal ? I apologize if my post lacks detail it's just that i'm not really good at solving issues like these.

iMac (27-inch, Late 2012), Mac OS X (10.1.x)

Posted on Jun 21, 2015 8:00 PM

Reply
25 replies

Jun 22, 2015 1:41 PM in response to TheCommerceComet

Install GPT Fdisk (aka gdisk).

Leave your Testdisk display and start a new Terminal Window. You need to use the following steps. If you see any error messages during the following steps, please stop and post back here with the error message. The following steps have values from your Testdisk output (and you can verify) in Steps 7 and 8. Please notice the '+' sign in step 8 (this is called offset notation). The text in parentheses is for informational purpose to describe the action being taken. Gdisk has one-character commands except when entering numbers.


Rebuild GPT4 using start/end offsets


  1. Sudo gdisk /dev/rdisk0
  2. P (print the full list of parts)
  3. D (delete)
  4. 4 (part 4)
  5. N (new part)
  6. 4 (part 4)
  7. 1655617536 ( - Start offset in bytes or the start point for Bootcamp part)
  8. +297906169 ( - Size offset, as opposed to End offset)
  9. 0700 (Windows part type)
  10. P (print list of all parts just to see what changes will be made)
  11. W (Write the new GPT)
  12. Y (Yes! really write the new GPT)

This will delete and re-write the GPT partition info for /dev/disk0s4.

Rebuild MBR to match the new GPT information thus resetting the Hybrid MBR. Use defaults for other questions (like partition codes). The only values that need modifications are the Boot flags and step 10. Accept all other defaults that Gdisk offers. Please see thesample Q&A as an example. These steps can be repeated if you make a mistake before you get to Step 12, otherwise start from Step 1 for these steps. Step 6 has numbers which are typed with a space between the numbers. If you get a message about additional space found, press 'n' and continue.

  1. Sudo gdisk /dev/rdisk0
  2. P (Print list of parts)
  3. R (Recover)
  4. O (print current Hybrid MBR)
  5. H (chooses Hybrid)
  6. Partitions numbers to be hybridized: 2 3 4
  7. Y (Good for GRUB question)
  8. N (part 2 boot flag)
  9. N (part 3 boot flag)
  10. Y (part 4 boot flag make NTFS bootable partition)
  11. O (print current Hybrid MBR)
  12. W (Write the new MBR)
  13. Y (Yes! write the new MBR)
  14. Reboot


Here is sample Q&A for this section. Please notice the Press Enter/Return.


Place EFI GPT (0xEE) partition first in MBR (good for GRUB)? (Y/N): Y


Creating entry for GPT partition #2 (MBR partition #2)

Enter an MBR hex code (default AF): Press Enter/Return

Set the bootable flag? (Y/N): N


Creating entry for GPT partition #3 (MBR partition #3)

Enter an MBR hex code (default AB): Press Enter/Return

Set the bootable flag? (Y/N): N


Creating entry for GPT partition #4 (MBR partition #4)

Enter an MBR hex code (default 07): Press Enter/Return

Set the bootable flag? (Y/N): Y


Test 1 - Does Bootcamp Volume show up in Finder?

Test 2 - Can you see files in Bootcamp Volume?

Test 3 - Can you select Bootcamp in System Preferences -> Startup Disk?

Test 4 - If Test 3 is successful, select Bootcamp and Click Restart.

I can't boot into my windows after resizing my partition

Welcome to Apple Support Community
A forum where Apple customers help each other with their products. Get started with your Apple ID.