The most common reasons you can't enable Secure Boot and how to fix them are:
- Secure Boot requires disabling CSM (Compatibility Support Module) in the BIOS. If you try to disable CSM but it re-enables on saving and exiting, it usually means something else is preventing the change. You first need to ensure your disk is formatted with GPT partition style rather than MBR, and your BIOS is set to UEFI mode rather than Legacy BIOS mode, as Secure Boot only works with UEFI and GPT.
- In the BIOS, under the Boot menu, you should disable CSM Support which then reveals the Secure Boot setting. Then you can enable Secure Boot and set its mode to Standard. Sometimes changing Secure Boot mode from Standard to Custom and back to Standard resets the keys and fixes issues with Secure Boot not activating fully.
- If you see a message like "system in setup mode! secure boot can be enabled when system in user mode," you may need to enroll platform keys first. In BIOS, going to Secure Boot key management and restoring factory keys can be necessary.
- Other hardware or OS incompatibilities can block enabling Secure Boot. Make sure devices like graphics cards are Secure Boot compatible, and uninstall incompatible OS versions or hardware if needed.
- If Secure Boot is enabled but not active after reboot, it often means keys are missing or not assigned properly. Restoring factory keys in BIOS secure boot key management usually activates it.
In summary, to fix Secure Boot enable issues:
- Confirm your disk uses GPT partition style.
- Set BIOS to UEFI mode, disable CSM.
- Enable Secure Boot, set mode to Standard, or toggle between Custom and Standard.
- If needed, restore or enroll Secure Boot keys in BIOS.
- Save BIOS settings and reboot.
Make sure to check your motherboard or PC manufacturer’s instructions as BIOS layouts vary and sometimes specific steps or BIOS updates are necessary.