When you go to <host>:<port>/workflow and "Instances", you will notice the workflow for the scheduled activation. You can terminate that workflow and scheduled activation should be stopped.

If you replace "https://www.site.com" with the actual IP of AEM instance(bypassing dispatcher), does the issues get resolved? If yes, the issue lies with the dispatcher.

Please get in touch with your CSM/TAM if you already a customer OR get in touch with sales team at [1] [1] https://www.adobe.com/request-consultation/experience-cloud.html

IF you have already migrated to 6.4, you should use sling model exporter[1] and export the content as json [1] https://docs.adobe.com/content/help/en/experience-manager-learn/foundation/development/develop-sling-model-exporter.html

If you have the list of pages, you can create a package from publish and install it on author. Once that is done, you can perform the normal activation and deactivation of pages.

This warning is caused by references to users (in "jcr:lastModified" or "jcr:created" properties), who do no longer exist. Please follow these steps to suppress the  messages: - Go to /system/console/slinglog- Log level - ERROR- Logger: com.adobe.granite.security.user.util.AuthorizableUtil- Log file...

Most Likely, this issue is caused by indexing. Check [1] to validate if indexes are corrupted or not updating every 5 seconds. [1] http://<host>:<port>/system/console/jmx/org.apache.jackrabbit.oak%3Aname%3Dasync%2Ctype%3DIndexStats

Do you get a response when you access "http://localhost:4502/crx/packmgr/service.jsp" directly from the browser?

Do you see anything in the upgrade.log?

Thanks, Dan for sharing!  Looks Good!