How to Fix 404 Not Found nginx/1.26.1 on App service

salman, Apologies for the delayed response from over the weekend.

Based on my understanding of your issue,

Just to highlight, You may FTP or SSH into App Service - please checkout this doc for the steps. Open an SSH session to a container in Azure App Service

You may also, navigate to your App Service via the Azure Portal.
Under the Development Tools section, select SSH then Go -->.

Modifying the default site config

You will want to make a copy of the existing configuration and place the file inside the /home/site directory.

cp

Once copied, edit the /home/site/default file and update the section below:

server

Creating the custom startup script

You will now need to create a custom startup script and save the file as /home/site/startup.sh

#!/bin/bash

In the custom startup script we are doing the following:

1. Overriding the existing /etc/nginx/sites-enabled/default file with the /home/site/default file.
2. Reloading the NGINX service to make the updates take effect.

Ref: Checkout this article for more info:

NGINX Rewrite Rules for Azure App Service Linux PHP 8.x

Deploy your app to Azure App Service using FTP/S

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