DotNet Core App can't find controller Method - asp.net-core

Question

I've got this .net core 2.2 app, and it works locally. It's got these two main projects, PictureLink.UI and PictureLink.API.
The UI side sends requests to POST and GET from the API side via the Angular frontend.
Locally, it works just fine. When it sends a GET to the UI side, it sends to URLs like: https://localhost:44343/UI/auth/DecodeJwtPayload <-- This works
And when it tries to access the API side, it sends to URLs like:
https://localhost:44343/API/photo/GetPhotos <-- This works
Locally, it works just fine.
Then I published it, and now the URLs are like:
https://{url}/UI/auth/DecodeJwtPayload <-- This works
And when it tries to access the API side, it sends to URLs like:
https://{URL}/API/photo/GetPhotos <-- And this returns a 404
I don't understand why it would work locally during testing and then stop working when we publish it.
Some articles suggested adding services.AddControllers() to ConfigureServices in Startup, but VS is telling me that's not a valid method.
I don't even know where to start looking. Is this a routing issue? And IIS issue? An AzureDevOps issue? A config issue?
I am so. Lost.

Answer 1

There are many reasons for the 404 error. You can try the following methods:
1.You need to publish your website and then point IIS website to the published folder.
2.Application pool must be set to No Managed code
3.Application Pool identity user IIS AppPool\{AppPoolName} must have read permissions on the published website folder. Change the identity of your application pool to ApplicationPoolIdentity. For application pool identity there will be user account with name IIS AppPool{Applicaiton Pool name} e.g. for DefaultAppPool the user account is IIS AppPool\DefaultAppPool so you can allow read/write access to your to Applicaiton Pool user on published application folder.
If you still can’t solve your problem, please publish your controller code and web.config file.