All stages green except the production deploy, which failed three runs in a row. Nobody changed anything. Where do you dig first?

An unchanged pipeline can fail because of environment state, external inputs or a latent artifact defect. Failures that start on an expiry boundary narrow the field to two suspects fast.

Grounded in researched DevOps, SRE and platform engineering interview loops, written to a senior-engineer editorial bar, and never padded to hit a word count.