ASP.net code update on AZURE server

I have an app running in AZURE, which I had turned off due to lack of use (scaled down to free server and stopped DevOps / app services). We now need to turn it back on, but when I reinstate the services, it doesn't work. I need someone who is very good with Azure admin and ASP.net code troubleshooting to help me with this.

Experts with Microsoft Azure development required.

You must be very conversant with Azure, have excellent knowledge of working with Visual Studio repos online, and know how to quickly troubleshoot code issues and update ASP.net code changes to match 2024 version and service requirements.

IMPORTANT NOTE: It may not be possible to get access to the server. All server-side work will be done by me, with you on a video call with sharing screens, where you will guide me.

As of now, we know that the code worked perfectly before the server was downgraded. Since we've brought it back online, we see the app site gives the following error:

HTTP Error 500.30 - ANCM In-Process Start Failure
Common solutions to this issue:
The application failed to start
The application started but then stopped
The application started but threw an exception during startup
Troubleshooting steps:
Check the system event log for error messages
Enable logging the application process' stdout messages
Attach a debugger to the application process and inspect
For more information visit: https://go.microsoft.com/fwlink/?LinkID=2028265

Further investigation has shown it uses a deprecated node, which gives some error messages around SSL, but I'm not an ASP.net developer and the original developers are no longer contactable. So I need someone who can get this back online quickly.