Imagine crafting a seamless microservices architecture with Feign clients to simplify REST calls, only to encounter the dreaded exception: IOException: Too Many Bytes Written. The error seems cryptic and out of place, often catching developers off guard during seemingly ordinary scenarios. Beneath its surface, however, lies a myriad of causes linked to payload sizes, response handling, and improper configurations. Understanding these nuances can save hours of debugging and pave the way for resilient APIs. In this article, we’ll explore why this error occurs, how to reproduce it, and actionable strategies to resolve it. From debugging Feign configurations to optimizing payloads, you’ll gain a detailed insight into tackling this challenge.