AuthenticationSupport service missing. Cannot authenticate request

@nico_weyens 

1. Check whether your Apache Sling Authentication Service Bundle is active or not (http://localhost:4502/system/console/bundles/)- if not active then try to activate it manually.
2. Stop the AEM instance - Go to folder crx-quickstart/repository/remove folder index -> Start the AEM
3. Go for a re-indexing - http://www.wemblog.com/2011/12/how-to-rebuild-index-in-cq5-wem.html
4. Check the ERROR log - if you are seeing any memory related logs (Java Heap Space (java.lang.OutOfMemoryError: Java heap space)) if yes, then try to increase the memory value in the JVM start script.

Regards,

Raja

Could you please check the disk usage as well in the server as well as through the /etc/reports/diskusage.html.

This way we can know we have the space but it is something problem with the segments. Also, if the segments get corrupted and we have sufficient disk space We need to run the segment consistency check once to confirm if there are any good revisions available to revert to refer[0].

[0] https://experienceleague.adobe.com/docs/experience-cloud-kcs/kbarticles/KA-16542.html?lang=de-DE

@nico_weyens 
Please check all the available existing error.log files(logs rotated with previous days) in your local instance before you get to notice the exact log statement - "AuthenticationSupport service missing".

Share the initial statement that logged as "Error" level. 

Recently ran into the issue in one of my local instance and the original/initial cause was  Java Heap Space (java.lang.OutOfMemoryError: Java heap space) which then eventually lead to "AuthenticationSupport service missing" - While setting up the new instance, I missed to configure the JVM options in start.bat and was using the default one.

Thanks