This is the leading cause in modern Opels. If a control module (like the BCM or Radio/Navigation unit) was replaced but not programmed correctly using SPS (Service Programming System), the software versions will clash.
Modern vehicles use a Controller Area Network (CAN-Bus) to allow different modules—like the Body Control Module (BCM), Engine Control Unit (ECU), and Infotainment system—to communicate. When a module is added, removed, or its programming is corrupted, the system detects a discrepancy in the "Maximum Configuration List," triggering the U2102-00 code. opel u2102-00