Hi @Ben Woodman
I would suggest reviewing Tutorial: Troubleshoot an App Service app with Azure Monitor for suggestions on how to monitor your app service. The AppServiceHTTPLogs
will help isolate which request(s) resulted in any 5xx/4xx errors. But also enabling application insights in addition will give you further insights into what led to a 5xx HTTP error code in the first place. Also, look at Diagnose and solve problems blade can also help you further investigate application errors you're seeing.