My deploy fails with system error message

I need advice to debug deploy https://app.netlify.com/sites/brent-clark/deploys/5e6577cfe4489e4cc1707794.
It fails with only error as “System Error”.

Hi @kingingcole! How frustrating. Seems like a temporary blip? Can you try again and tell us if you are still seeing this error? that would be very helpful. thanks.

@kingingcole This has been fixed on our end. Please let us know if you experience this error again!

we have figured out the root cause of this (it was quite tricky to pin down)

more details here: Bug Fixed: Some builds fail immediately with System Error