@Dheamohammed said:
i face 401 problem
when i use the api in my learning project i have problem in console it show to me 401 error

Can you tell us which of the 401 errors is occurring?

See the list of TMDb server error warnings here.
https://www.themoviedb.org/documentation/api/status-codes
In your case:

Code    HTTP    Message  
3       401     Authentication failed: You do not have permissions to access the service.
7       401     Invalid API key: You must be granted a valid key.
10      401     Suspended API key: Access to your account has been suspended, contact TMDb.
14      401     Authentication failed.
16      401     Device denied.
17      401     Session denied.
30      401     Invalid username and/or password: You did not provide a valid login.
31      401     Account disabled: Your account is no longer active. Contact TMDb if this is an error.
32      401     Email not verified: Your email address has not been verified.
33      401     Invalid request token: The request token is either expired or invalid.
34      401     The resource you requested could not be found.
35      401     Invalid token.
36      401     This token hasn't been granted write permission by the user.
38      401     You don't have permission to edit this resource.
39      401     This resource is private.  

Can you let us know which of these error responses you received?

I'm getting this same 401 error. In my case it says

401     Invalid API key: You must be granted a valid key.

However, my key is valid. What seems to be the problem?

Thanks

@Argonath said:
I'm getting this same 401 error. In my case it says

401     Invalid API key: You must be granted a valid key.  

However, my key is valid. What seems to be the problem?
Thanks

You can check if your API Key is working properly.
Just replace THE_KEY with your Key and open it in a new tab or window in your browser.

https://api.themoviedb.org/3/movie/550?api_key=THE_KEY  

If it's working then the problem isn't with your API Key.

The problem must be in the code that is building your API Request, or something like that,
and is sending the Request to the TMDb Server.

It is very common to find people here with this type of problem.
A little mistake, a copy and paste with an extra space, or less character, an exchange of characters,
a quote left, use a dash when it should be underline, in short a typo and the answer can be that.
Even if the API Key is correct. The Requisition is that it has a little mistake.

I will place 6 API requests here. The first 5 with error.
You can see that the API Key is correct but the answer is Invalid API key or could not be found.

1 https://api.themoviedb.org/3/movie/550&api_key=THE_KEY  
2 https://api.themoviedb.org/3/movie/550/api_key=THE_KEY  
3 https://api.themoviedb.org/3/movie/550?api-key=THE_KEY  
4 https://api.themoviedb.org/3/movie/550? api_key=THE_KEY    
5 https://api.themoviedb.org/3/movie/'550'?api_key=THE_KEY  
6 https://api.themoviedb.org/3/movie/550?api_key=THE_KEY    

My suggestion is to check if there is any way for you to view the API Request that your APP is sending to the TMDb server.
Not the construction of the code, but the requisition built, final.
If possible, post the Request here.
If this is not possible, then you need to check in your code if there is a mistake, like the mistake in the examples above.
The error is usually in this segment of the API Request: ....?api_key=12345....

The code was working fine before, but I haven't been using it for a while. I only use it for academic purposes. But for some reason the API key became invalid. I regenerated a new one and everything worked as before.

Thanks