401 Error when trying to make a REST API call to site

The 401 (Unauthorized) status code indicates that the request has not been applied because it lacks valid authentication credentials for the target resource. The server generating a 401 response MUST send a WWW-Authenticate header field containing at least one challenge applicable to the target resource.

1. How do I fix a 401 unauthorized error in API?
2. Why do I get 401 unauthorized error?
3. How do I fix a 401 unauthorized error in Salesforce?
4. What does the HTTP status code 401 indicate?
5. What is the difference between 401 and 403 error?
6. What is a 402 error?
7. What does 401 Authorisation required mean?
8. Which of the following cases will lead to a 401 response status code under the specifications of restful API design?

How do I fix a 401 unauthorized error in API?

Check that the authentication credentials you are passing along in the request are correct and belong to an active token.
...
API Error 401: Unauthorized

1. The authentication credentials are missing.
2. The authentication credentials are incorrect.
3. The authentication credentials belong to a token that has been revoked.

Why do I get 401 unauthorized error?

The 401 Unauthorized error is an HTTP status code that means the page you were trying to access cannot be loaded until you first log in with a valid user ID and password. If you've just logged in and received the 401 Unauthorized error, it means that the credentials you entered were invalid for some reason.

How do I fix a 401 unauthorized error in Salesforce?

This error means that there is an expired session in your Salesforce. It may due to your connection has been invalidated or it has not been given the access to API. Solution: Reconnect your Salesforce connection, ensure that you are authorized to access the described object on the step, and re-run the job again.

What does the HTTP status code 401 indicate?

2 401 Unauthorized. The request requires user authentication. The response MUST include a WWW-Authenticate header field (section 14.47) containing a challenge applicable to the requested resource.

What is the difference between 401 and 403 error?

In summary, a 401 Unauthorized response should be used for missing or bad authentication, and a 403 Forbidden response should be used afterwards, when the user is authenticated but isn't authorized to perform the requested operation on the given resource.

What is a 402 error?

The HTTP 402 Payment Required is a nonstandard client error status response code that is reserved for future use. Sometimes, this code indicates that the request can not be processed until the client makes a payment.

What does 401 Authorisation required mean?

Sometimes, instead of “401 Unauthorized” you could also get the message “401 Authorization Required.” Both basically mean that you don't have permission for the requested website and must log in first.

Which of the following cases will lead to a 401 response status code under the specifications of restful API design?

A 401 error response indicates that the client tried to operate on a protected resource without providing the proper authorization. It may have provided the wrong credentials or none at all. The response must include a WWW-Authenticate header field containing a challenge applicable to the requested resource.