---
title: "Handling HTTP 429 Errors and Request Throttling in Azure Cosmos DB"  
description: "Handling HTTP 429 Errors and Request Throttling in Azure Cosmos DB"  
author: "Pedro Araez"  
published: 2026-09-17  
updated: 2026-09-17  
canonical: https://www.mindstick.com/forum/162178/handling-http-429-errors-and-request-throttling-in-azure-cosmos-db  
category: "Azure Cosmos DB"  
tags: ["Cosmos DB 429", "Request Units", "Throttling", "Azure SDK", "Retry Policy"]  
reading_time: 1 minute  

---

# Handling HTTP 429 Errors and Request Throttling in Azure Cosmos DB

When your application exceeds the provisioned Request Units per second allocated to a Cosmos DB container, the service returns an **HTTP 429** error. This response signals that requests are being throttled to protect system availability.

## Common Causes of Throttling

Throttling usually stems from sudden traffic spikes, inefficient cross-partition queries, or poorly distributed partition keys leading to localized hot spots. While short bursts are normal, persistent 429 errors mean your system needs client-side retry tuning or scaled throughput.

## Configuring Client SDK Retry Options

The Azure SDKs automatically retry throttled requests, but default values might not suit high-throughput background processing jobs. You can explicitly customize retry attempts and wait times during client initialization:

```cs
// Configure custom retry settings to gracefully handle throughput spikes
CosmosClientOptions clientOptions = new CosmosClientOptions()
{
    // Increase maximum retry attempts beyond the default value of 9
    MaxRetryAttemptsOnThrottledRequests = 15,
    // Set maximum accumulated wait time for retries to 30 seconds
    MaxRetryWaitTimeOnThrottledRequests = TimeSpan.FromSeconds(30)
};

// Instantiate the client with adjusted resilience options
CosmosClient client = new CosmosClient("ACCOUNT_ENDPOINT", "ACCOUNT_KEY", clientOptions);
```

If increasing retry parameters does not clear the 429 responses, consider switching container throughput to autoscale mode or converting low-traffic workloads to serverless capacity.


---

Original Source: https://www.mindstick.com/forum/162178/handling-http-429-errors-and-request-throttling-in-azure-cosmos-db

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