# \[App\]\[Pro\] Viessmann App for Homey Pro

**URL:** <https://community.homey.app/t/app-pro-viessmann-app-for-homey-pro/116744>\
**Category:** Apps\
**Tags:** app, homey-pro\
**Created:** [September 26, 2024, 12:33pm UTC](https://community.homey.app/t/app-pro-viessmann-app-for-homey-pro/116744 "2024-09-26T12:33:22Z")\
**Posts on this page:** 1\
**Showing post:** 302

<div class="post-metadata">

**Author:** ![Sjoors](https://sea1.discourse-cdn.com/flex025/user_avatar/community.homey.app/sjoors/32/79673_2.png) [@Sjoors](https://community.homey.app/u/Sjoors)\
**Post date:** [December 5, 2025, 6:20pm UTC](https://community.homey.app/t/app-pro-viessmann-app-for-homey-pro/116744/302 "2025-12-05T18:20:56Z")

</div>

Hi Kenny,

I get exaclty the same error as mentioned above, Invalid grant. It was working for months until the 1ste of december. I removed the client from the developers portal and created a new one. New ID used. then this error Error: Client authentication failed

The other Viessmann app in the Homey store has the same problem. So probably something changed in the API

---

_[View the full topic](https://community.homey.app/t/app-pro-viessmann-app-for-homey-pro/116744)._