OverloadedError
anthropic.errors.OverloadedError (HTTP 529)
Stack trace
anthropic.errors.OverloadedError: 529 Server Busy - The Anthropic API is currently overloaded and cannot process the request.
Why it happens
This error occurs when Anthropic's servers are experiencing high traffic or resource constraints, causing them to reject new requests temporarily with a 529 status code. It signals that the client should retry after some delay.
Detection
Monitor API responses for HTTP status 529 or catch anthropic.errors.OverloadedError exceptions to detect server overload before your app crashes.
Causes & fixes
Sending too many requests in a short time exceeding Anthropic's capacity
Implement exponential backoff and retry logic with delays to reduce request rate during high load.
Burst traffic spikes causing temporary server overload
Use client-side rate limiting or queue requests to smooth out bursts and avoid hitting overload.
No retry mechanism on OverloadedError exceptions
Catch OverloadedError exceptions and retry the request after a delay, increasing wait time on repeated failures.
Code: broken vs fixed
from anthropic import Anthropic
client = Anthropic(api_key='sk-...')
response = client.completions.create(model='claude-2', prompt='Hello') # This line may raise OverloadedErrorimport os
from anthropic import Anthropic, errors
import time
client = Anthropic(api_key=os.environ['ANTHROPIC_API_KEY'])
for attempt in range(5):
try:
response = client.completions.create(model='claude-3-5-haiku-20241022', prompt='Hello')
print(response)
break
except errors.OverloadedError:
wait = 2 ** attempt
print(f'Server busy, retrying in {wait} seconds...')
time.sleep(wait)
else:
print('Failed after retries due to server overload.')Workaround
Wrap Anthropic API calls in try/except OverloadedError, then wait and retry manually with increasing delays to avoid immediate failure.
Prevention
Implement robust client-side rate limiting and exponential backoff retries to prevent overwhelming Anthropic servers and avoid 529 errors.