Error codes

BOOTMGR is compressed

What it means

Someone compressed the boot manager file to save space, and the firmware cannot read a compressed boot manager.

Common causes

• A disk-cleanup or compression tool run on the system partition
• Manual NTFS compression of C:\
• A third-party optimiser

How to fix it

1. Start the PC from the Windows install stick or recovery drive, then choose Repair your computer > Troubleshoot > Advanced options > Command Prompt.
2. In the recovery Command Prompt run bootrec /fixboot to write a fresh boot manager.
3. Then turn off NTFS compression for the system drive: right-click C: > Properties > General, untick Compress this drive.