If your app broke this morning, you're not alone. Thousands of developers worldwide are waking up to 410 errors right now. Claude 4 Opus and Sonnet 4 were permanently retired today as part of Anthropic's planned deprecation cycle. The good news: the fix takes 5 minutes, and you can actually save 67-99% on your API costs.
What Happened Today
At midnight UTC on June 15, 2026, Anthropic flipped the switch on Claude 4. Every API endpoint that references claude-4-opus or claude-4-sonnet now returns a 410 Gone error. Here's the timeline of what's happening:
The 5-Minute Fix
Migrating from Claude 4 is the simplest model migration you'll ever do. The API format, SDK, authentication, and parameters are identical. You change one string:
Find Every Claude 4 Reference
Run this in your project root to find all files that need updating:
grep -r "claude-4-opus\|claude-4-sonnet" --include="*.js" --include="*.ts" --include="*.py" --include="*.json" .Update the Model ID
Replace the deprecated model name with the official successor:
// Before (returns 410 Gone)
model: "claude-4-opus"
// After (official successor — same API, same key)
model: "claude-opus-4-8"
// For Sonnet:
model: "claude-sonnet-4-6"No other code changes needed. Your existing API key works as-is.
Test and Deploy
Make 5-10 test calls to verify the new model works with your prompts. Then deploy. Your app is back online.
Calculate your new costs instantly
See exactly what you'll pay with Claude Opus 4.8 vs alternatives. Free calculator — upgrade for alerts.
What You Were Paying vs What You Can Pay
The Claude 4 shutdown is actually an opportunity to cut your costs dramatically. Here's the comparison (per 1M tokens):
Cheapest Alternatives (Ranked by Savings)
If you want to save even more than the official successors, here are the best options:
Want to see all 42 alternatives with live pricing? Check our Claude 4 Migration Hub — 18 head-to-head comparisons, migration calculators, and code snippets for every alternative. Or use our Migration Advisor to find your cheapest option in 60 seconds.
FAQ — What Developers Are Asking Right Now
Is Claude 4 coming back?
No. The shutdown is permanent. Anthropic has fully transitioned to the 4.x generation. The model IDs claude-4-opus and claude-4-sonnet will never return.
Does my API key still work?
Yes, if you're staying with Anthropic. Your existing API key works with Claude Opus 4.8 and Sonnet 4.6 — you just change the model name string. If switching providers, you'll need a new key.
What if I already migrated but still see errors?
Run the grep command above to find any remaining references to the deprecated model IDs. Check config files, environment variables, and hardcoded strings. Also verify your API key has sufficient credits.
Is there a drop-in replacement with zero code changes?
For claude-4-sonnet, use claude-sonnet-4-6 — same context window, same quality, 50% cheaper. For claude-4-opus, use claude-opus-4-8. These are the official Anthropic successors with identical API formats.
What if I need help choosing an alternative?
Use our Migration Advisor — answer 3 questions about your use case, budget, and quality requirements, and get a personalized recommendation in 60 seconds. Free, no signup required.
Calculate Your New Costs
See exactly what you'll pay after migration. Compare Claude Opus 4.8, Sonnet 4.6, DeepSeek, GPT-5.5, and Gemini — all with real-time pricing.
Open Cost Calculator →Don't just migrate — optimize
Most developers pick the first replacement they find. Pro users get personalized model routing — use cheap models for 80% of tasks, premium models only when needed. Save up to 40% on your new provider.
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