Viessmann SG-Ready Heatpump - unexpected status 400

[SpaceRichard]

Describe the bug

I'm about to add my heat pump, I successfully added the pump already to HA but with evcc is get the following error:

Status: fehlgeschlagen [prüfen](http://homeassistant.neo:8123/api/hassio_ingress/KJ6X4DrW6AzIZdIVjnYDRZQ2g53rMIH71TYvO8UKNjA/#)
cannot create charger type 'template': cannot create charger type 'sgready': cannot create auth type 'viessmann': unexpected status 400

Client ID, Gateway Serial, Installation ID are present.

Steps to reproduce

1. enter all details to Add Viessmann Heatpump
2. click "check"

Configuration details

Can's save the config of Viessmann/Heatpump so this part is not within the config

Log details

[viessmann] TRACE 2025/08/07 10:39:00 GET https://iam.viessmann-climatesolutions.com/idp/v3/authorize?client_id=XXX&code_challenge=L4piNKjEQDlJn-KVonuZnsZTe35xpSnVy8mDj8wNQZg&code_challenge_method=S256&redirect_uri=http%3A%2F%2Flocalhost%3A4200%2F&response_type=code&scope=IoT+User+offline_access&state=mxxhUyrPtocMWuqD
[viessmann] TRACE 2025/08/07 10:39:00 {"error":"invalid_request", "error_description":"Invalid redirection URI."}
[viessmann] TRACE 2025/08/07 10:39:30 GET https://iam.viessmann-climatesolutions.com/idp/v3/authorize?client_id=XXX&code_challenge=HpuNe048s6HfNp03zDf7Homsvs5sEJepk_CIC-19SxE&code_challenge_method=S256&redirect_uri=http%3A%2F%2Flocalhost%3A4200%2F&response_type=code&scope=IoT+User+offline_access&state=bKCbtIJkD9RL0qt3
[viessmann] TRACE 2025/08/07 10:39:30 {"error":"invalid_request", "error_description":"Invalid redirection URI."}
[viessmann] TRACE 2025/08/07 10:40:44 GET https://iam.viessmann-climatesolutions.com/idp/v3/authorize?client_id=XXX&code_challenge=1J203av8K7kGLIt7zwZvjM5r-88masoVkMDCwWCjwWg&code_challenge_method=S256&redirect_uri=http%3A%2F%2Flocalhost%3A4200%2F&response_type=code&scope=IoT+User+offline_access&state=mU6ilEoetUmiF4kY
[viessmann] TRACE 2025/08/07 10:40:44 {"error":"invalid_request", "error_description":"Invalid redirection URI."}
[viessmann] TRACE 2025/08/07 10:53:45 GET https://iam.viessmann-climatesolutions.com/idp/v3/authorize?client_id=XXX&code_challenge=yeoWt2DCWV2gbnLhe8Wr4_sK1637v5MUutKm3IyraRw&code_challenge_method=S256&redirect_uri=http%3A%2F%2Flocalhost%3A4200%2F&response_type=code&scope=IoT+User+offline_access&state=EewiBrFf6LbqB335
[viessmann] TRACE 2025/08/07 10:53:45 {"error":"invalid_request", "error_description":"Invalid redirection URI."}

What type of operating system or environment does evcc run on?

HomeAssistant Add-on

External automation

• I have made sure that no external automation like HomeAssistant or Node-RED is active or accessing any of the mentioned devices when this issue occurs.

Nightly build

• I have verified that the issue is reproducible with the latest nightly build

Version

0.207.1

[SpaceRichard]

Could it be that the Client can only be used for one connection? But I can't see any option to add another client.

According the Error: Invalid redirection URI.
I added "http://localhost" to the redirected URI - still the same error - don't know if it needs more time to update in the background.

[andig]

/cc @mpollmeier