Diagnosing Buildpack Errors in Heroku Release Logs

Heroku’s Logplex aggregates dyno logs, but buildpack failures sometimes hide the exact error line within the release log, creating uncertainty about root cause identification.

When a deployment fails with “Failed to start process,” the buildpack error may be omitted or truncated, preventing precise diagnosis.

Identifying the precise log entry that reveals the failing buildpack step is essential for reliable debugging. What log format or annotation would make the exact buildpack failure visible, and does the `heroku logs --release ` command behave consistently across CLI versions?