while publishing to azure set your reply url to your proper application url.
if your test environment and production environment are different then while publishing to production you need to change that url to your production url insted of test url
Question
ACS50001: ACS50001: Relying party with identifier 'https://ABC.onmicrosoft.com/ABCTest' was not found.
Solution
while publishing to azure set your reply url to your proper application url.
if your test environment and production environment are different then while publishing to production you need to change that url to your production url insted of test url
OTHER TIPS
here is the option for multi-tenant. if you are using two active directory or more then you need to set multi tenant= yes