Unable to install macOS High Sierra due to ‘failure to validate firmware’

Number:rdar://2939675 Date Originated:7/10/17
Status: Resolved:
Product: Product Version:
Classification: Reproducible:
Please provide a descriptive title for your report:
Unable to install macOS High Sierra due to ‘failure to validate firmware’

What are you seeing an issue with?

What type of issue are you reporting?
Incorrect/Unexpected Behavior

What does the installation/setup/migration issue you are seeing involve?
Upgrade install

In which build did you encounter this bug?

When did you first experience this problem?
In a version of macOS Sierra prior to 10.12.5

Please describe the issue and what steps we can take to reproduce it:
When attempting to upgrade to the macOS High Sierra public-beta, my Mac Pro shows an “unable to verify firmware” error, and forces me to cancel the upgrade and reboot back into Sierra.

How often does this problem occur?
It happens every time

Does this prevent you from using this version of macOS?
The issue prevents me from using macOS at all


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