How a single space broke OpenSearch backups - and how Aiven fixed it for our customers

Aiven's engineering team addressed a critical issue where a single space character in a filename caused OpenSearch backup failures, affecting their customers' disaster recovery processes. The bug was traced to the K-Nearest Neighbors (k-NN) plugin within OpenSearch, which struggled with spaces in filenames despite being technically permissible on operating systems. After identifying the problem, Aiven advised customers to avoid using spaces in index names and implemented a guardrail to prevent upgrades to OpenSearch v2.x if spaces were detected, while the issue was officially resolved in OpenSearch v2.17. This scenario highlights Aiven's commitment to providing reliable, managed OpenSearch services, allowing customers to focus on their core offerings without technical disruptions.