API compatibility for AEM upgrade from AEM 6.4 to 6.5

Upgrading to AEM 6.5

1) Upgrading to AEM as a Cloud Service

2) Upgrading to AEM 6.5 AMS - Adobe Managed Service on Cloud Manager

you can check deprecated api here:

https://helpx.adobe.com/experience-manager/6-5/sites/developing/using/reference-materials/javadoc/deprecated-list.html

The deprecated APIs will continue to work on AEM 6.5 without any change. However, it is recommended to change the deprecated APIs with their corresponding updated APIs.

CloudManager code scanning

upgrade to AEM 6.5 is to be able to start using Cloud Manager (CM) to perform automated builds to the various environments (Dev, UAT, Stage and Prod).

https://experienceleague.adobe.com/docs/experience-manager-cloud-manager/using/how-to-use/understand-your-test-results.html?lang=en#how-to-use

Pattern Detector:

https://experienceleague.adobe.com/docs/experience-manager-65/deploying/upgrading/pattern-detector.html?lang=en#upgrading

This feature allows you to check existing AEM instances for their upgradability by detecting patterns in use that:

Violate certain rules and are done in areas that will be affected or overwritten by the upgrade
Use an AEM 6.x feature or an API that is not backwards compatible on AEM 6.5 and can potentially break after upgrade.