The problem

After updating to Home Assistant Core 2025.8.0, my myStrom Switch CH v1 no longer works. It is displayed as "unavailable" in the UI and when I click the entity, the message appears that "this device is no longer provided".

However:

• The device is still reachable via the myStrom app and its local IP.
• Other myStrom devices (CH v2) continue to work without any issue.
• I use the UI-based integration, not YAML.

This issue only affects the CH v1 model, and it worked fine in 2025.7.4. After restoring that version from backup, the switch was immediately usable again without any changes.

This suggests a breaking change in 2025.8.0 that silently breaks compatibility with older myStrom firmware or response formats.

What version of Home Assistant Core has the issue?

2025.8.0

What was the last working version of Home Assistant Core?

2025.7.4

What type of installation are you running?

Home Assistant Supervised

Integration causing the issue

mystrom

Link to integration documentation on our website

https://www.home-assistant.io/integrations/mystrom/

Diagnostics information

No response

Example YAML snippet

Anything in the logs that might be useful for us?

Additional information

No response