Mac OS X prevents write to MBR after Win 10 update

Discussion in 'Installation and Configuration of Parallels Desktop' started by C-String, Nov 10, 2017.

  1. C-String

    C-String Bit poster

    Now, when VM tries to start Windows 10 it gets caught in a loop. Originally running Parallels 11 (now Parallels 13) with Yosemite, I accepted Windows update and was surprised by the popup window saying the Mac OS had prevented writing to MBR on Bootcamp partition. Now I seem to be trapped between old and new with no access to either. The virtual Windows machine would interrupt its boot and try to revert to earlier version but never completed that task either. Never had this experience before with any previous 6 versions of Parallels and hope there's a way to fix the Master Boot Record on the bootcamp without completely re-constructing the Windows virtual machine. Similar experiences and suggestions would be greatly appreciated
  2. PaulChristopher@Parallels

    PaulChristopher@Parallels Product Expert Staff Member

    Hi @C-String, in order to find out whether your disk has GPT or MBR partition table, please go to Control Panel -> Administrative Tools -> Computer Management, and select Disk Management. Enter disk Properties -> Volumes -> the Partition style: entry will show as either Master Boot Record (MBR) or GUID Partition Table (GPT). Please check out the instructions outlined in this article to fix the issue.

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