A Lambda function issues queries to an Amazon Aurora MySQL DB instance and, during tests, encounters too many connections errors on the DB. Which option solves this problem with the least operational overhead?

Amazon RDS Proxy is the most suitable solution with the least operational overhead. It pools and shares database connections, effectively managing a large number of concurrent connections from serverless applications like Lambda functions. This prevents the "too many connections" error without requiring significant application changes. Creating a read replica would offload read traffic, but the Lambda function might still overwhelm the primary instance with write operations or if all queries are directed to the replica, it could still face connection issues. Rebuilding the application to use DynamoDB is a significant architectural change with high operational overhead, not a quick fix for connection errors. Enabling Multi-AZ provides high availability and failover, but it does not inherently solve the problem of too many concurrent connections to a single database endpoint.