Optimistic Updates & Rollback¶

When you switch a Homematic device in Home Assistant, the UI updates immediately — without waiting for the CCU to confirm the command. This is called an optimistic update. It makes the interface feel fast and responsive.

Behind the scenes, a safety timer starts. If the CCU does not confirm the command within 30 seconds, Home Assistant assumes the command did not succeed and reverts the UI back to the previous state. This is called an optimistic rollback.

How it works¶

You press "On"
    │
    ▼
UI shows "On" immediately          ← optimistic update
    │
    ├── CCU confirms within 30s    → state stays "On" ✅
    │
    └── No confirmation after 30s  → UI reverts to "Off" ⚠️  (rollback)

1. You switch a device (e.g., turn on a light)
2. Home Assistant shows the new state right away — you see instant feedback
3. The command is sent to the CCU via RPC
4. A 30-second timer starts
5. If the CCU confirms: The timer is cancelled, the state is confirmed — everything is fine
6. If no confirmation arrives: The state reverts to the previous value and a warning is logged

Rollback reasons¶

When a rollback occurs, a warning message appears in the Home Assistant log. The message includes the reason for the rollback:

Example log message¶

Optimistic rollback for Power Galerie/STATE: False -> True (reason=timeout, age=30.0s)

This means: - The device Power Galerie was switched to On (True) - The CCU did not confirm within 30 seconds - The UI reverted back to Off (False)

Common causes for timeout rollbacks¶

A timeout rollback means the command was sent, but the CCU did not respond. Typical causes:

Communication issues¶

• Network problems between Home Assistant and the CCU (e.g., after SSL certificate changes, firewall rules, or network reconfiguration)
• CCU overloaded — the CCU is busy and cannot process commands in time

Radio (RF) issues¶

• Duty cycle exhausted — BidCos-RF has a 1% duty cycle limit. If many devices are switched simultaneously, the CCU may run out of send budget
• Weak signal — the device is too far from the CCU or a repeater
• Interference — other 868 MHz devices are causing radio collisions

Device issues¶

• Device unreachable — the device is powered off, defective, or out of range
• Battery empty — battery-powered devices may not respond when the battery is low

Troubleshooting¶

Step 1: Verify the device works via CCU¶

1. Open the CCU web interface in your browser (e.g., http://<CCU-IP>)
2. Go to Status und Bedienung → Geräte
3. Find the affected device and switch it manually

If the device does not switch via the CCU either, the problem is on the CCU/RF side (not Home Assistant).

Step 2: Check the CCU duty cycle¶

1. Open the CCU web interface
2. Go to Einstellungen → Systemsteuerung → Funk-Schnittstellen
3. Check the Duty Cycle percentage for BidCos-RF

If the duty cycle is above 90%, the CCU cannot send more commands. Wait for it to reset (resets every hour) or reduce the number of simultaneous commands.

Step 3: Enable debug logging¶

1. In Home Assistant, go to Settings → Devices & Services
2. Find your Homematic(IP) Local integration and click on it
3. Click "Enable debug logging" (the bug icon at the top)
4. Trigger the automation that causes the rollback
5. Wait 30 seconds for the rollback to appear
6. Go to Settings → System → Logs
7. Click "Download full log" (top right)
8. Disable debug logging again (same path as step 2–3)

In the debug log, look for: - set_value entries for the affected devices — confirms the command was sent - event entries for the same devices — shows if the CCU sent a confirmation - Any error messages related to the affected interface

Step 4: Check for recent changes¶

Rollbacks that suddenly appear after a configuration change often point to:

• SSL/TLS changes — adding HTTPS to Home Assistant can affect the XML-RPC callback connection if the CCU cannot reach the new endpoint
• Network changes — new router, firewall, VLAN, or IP address changes
• CCU firmware updates — may change default settings or reset interface configurations

Configuration¶

The rollback timeout is configured via TimeoutConfig.optimistic_update_timeout (default: 30 seconds). This is not configurable through the Home Assistant UI — it is a library-level setting that applies to all devices.

The 30-second default is chosen to balance: - Fast feedback — users are notified within 30 seconds if a command failed - Tolerance for slow devices — battery-powered devices and busy networks may need several seconds to respond