Tesla Fleet Integration: Getting "Error resolving OAuth token: 400, message='Bad Request'" on installation

Configuration
1

I'm completely stuck trying to get the Tesla Fleet integration installed. I'm following the instructions here.

  • I've created a Tesla developer account
  • I've created my application (I already have my own website to store the public key at)
  • I have a Client ID and Client Secret from the developer site

When I try to install the Tesla Fleet integration, I experience the following things:

  • I'm told: "This step requires you to visit an external website to be completed." and I click the button to visit the external site
  • This opens a new browser tab to (Tesla Auth) where I submit my username, password, and MFA key
  • The web page momentarily says something like "Authentication successful" and then I'm presented with a page at Link to OAuth2 Authorize Callback – My Home Assistant informing me that I'm about to be redirected to my local HA URL.
  • I click "Link Account"
  • The tab disappears
  • The original tab I was installing the integration from now has a pop-up saying: "OAuth authorization error while obtaining access token."
  • The logs get an entry reading: "ERROR (MainThread) [homeassistant.helpers.config_entry_oauth2_flow] Error resolving OAuth token: 400, message='Bad Request', url='Tesla Auth'"

I've verified that the client ID and client secret are valid by using the manual partner token generation request described on this Tesla page.

I was able to self-generate a keypair by following this Tesla page and put the private key at config/tesla_fleet.key and the public key at my website's .well-known/appspecific/com.tesla.3p.public-key.pem location, which, as I expected, didn't help.

The Client Details I have at the Tesla Developer site are:
Allowed Origin(s): https://<domain_redacted>/
Allowed Redirect URI(s): https://my.home-assistant.io/redirect/oauth
Allowed Returned URL(s): (empty)

I guess this is all to say that I can probably do all of the key setup and token generation manually if I just knew where to put all of the data in the HA filesystem, but I'd really prefer that the documented setup procedure just work. I'm trying my best to follow the steps to the letter, but it keeps failing.

Suggestions?

2

Exact same issue here,
Checked everything and all seems ok. Than double checked it with ChatGPT and that led me to this post as according to Chat all is fine.

I am running :

  • Installation methodHome Assistant OS
  • Core2026.8.0
  • Supervisor2026.07.5
  • Operating System18.2
  • Frontend20260729.5

Error that I get :
Logger: homeassistant.helpers.config_entry_oauth2_flow
Source: helpers/config_entry_oauth2_flow.py:523
First occurred: August 8, 2026 at 1:25:06 PM (4 occurrences)
Last logged: 6:13:37 PM

Error resolving OAuth token: 400, message=‘Bad Request’, url=‘Tesla Auth’

As far as I can judge (and ChatGPT too) all configuration is fine.
So anyone here that can help with further debugging ?

3

I’m new to Home Assistant and have had the same ‘Bad Request’ issue after using ChatGPT. I made a change to my Tesla application form by changing the title from ‘Home Assistant’ as suggested by ChatGPT to one that I hoped would be unique.

Later, Tesla emailed to notify me that the application had been approved and that Home Assistant was now linked to my Tesla account. I then tried again to install the Integration. This time, the 400 Error disappeared, and the integration was successfully installed.

I cannot say with any certainty whether the title of ‘Home Assistant’ on the application form was the cause of the problems, but it may be worth looking into.

I hope this helps.