# 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
```


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# Agent Instructions: Querying This Documentation

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

Perform an HTTP GET request on the current page URL with the `ask` query parameter:

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

The question should be specific, self-contained, and written in natural language.
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.