The two models that shipped with the Sonnet 4 / Opus 4 generation last May hit their end-of-life on June 15. Any code still pointing at claude-sonnet-4-20250514 or claude-opus-4-20250514 will now get errors. Migration targets are claude-sonnet-4-6 for Sonnet and claude-opus-4-8 for Opus — both were available well before the cutoff, so this shouldn't be a surprise, but it's worth a sweep of any hardcoded model IDs in configs and CI. Two related items remain live: claude-opus-4-1-20250805 is deprecated (June 5) but doesn't retire until August 5, giving a two-month runway; and claude-mythos-preview retires June 30 with claude-mythos-5 as the successor. The deprecation page at platform.claude.com has the full table.