> For the complete documentation index, see [llms.txt](https://docs.blynk.io/en/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://docs.blynk.io/en/blynk.cloud/device-https-api/troubleshooting.md).

# HTTPS API Troubleshooting

* All HTTPS API are case-sensitive. Request path and query parameters letter-case shouldn't be changed.
* In case you're getting the `Invalid token.` response from the HTTPS API,

  and you're sure the device auth token is correct - it could be a GEO DNS issue.

{% hint style="info" %}
You can get the **Device auth token** in [Device info](https://bit.ly/BlynkSimpleAuth).
{% endhint %}

{% hint style="warning" %}
Due to current GeoDNS settings you need to put server address with suffix manually depending on your region:\
<https://fra1.blynk.cloud/> – Frankfurt\
<https://lon1.blynk.cloud/> – London\
<https://ny3.blynk.cloud/> – New York\
<https://sgp1.blynk.cloud/> – Singapore\
<https://blr1.blynk.cloud/> – Bangalore

The server region can be found in the right bottom corner of the web interface.
{% endhint %}

Using the wrong region will result in an HTTP status of `308 Permanent Redirect` with the correct URL in the `Location` header value in the response. The device must repeat the request with the correct URL and save the correct region for future requests.\
Example HTTP redirect response:

```http
HTTP/1.1 308 Permanent Redirect
Content-Length: 0
Location: https://ny3.blynk.cloud/external/api/isHardwareConnected?token=P-0ekUL3EjrEkE_UnIIzsIggqyQXYd0z
```


---

# Agent Instructions
This documentation is published with GitBook. GitBook is the documentation platform designed so that both humans and AI agents can read, navigate, and reason over technical content effectively. Learn more at gitbook.com.

## Querying This Documentation
If you need additional information that is not directly available in this page, you can query the documentation by asking a question.

Perform an HTTP GET request on the following URL with the `ask` and `goal` query parameters:

```
GET https://docs.blynk.io/en/blynk.cloud/device-https-api/troubleshooting.md?ask=<question>&goal=<user_goal>
```

`ask` is the immediate question: it should be specific, self-contained, and written in natural language.
`goal` is what the user is ultimately trying to achieve, the reason they need the answer. Sharing it helps GitBook give you a better, more relevant answer. A goal is most helpful when it describes the outcome the user wants rather than restating the question. For example, with `ask=how do I create an API token`, a goal like `automate deployments from our CI pipeline` lets GitBook tailor the answer to that use case.

The response will contain a direct answer to the question and relevant excerpts and sources from the documentation.

Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.