In AEM 6.5 there is no out-of-the-box (OOTB) solution to archive and restore content fragments like there is for pages. If this is required - you have to create a custom service or event handler - before deleting a content fragment, move it to an "archive" location in the JCR repository. same for re...

can you raise a Adobe Support ticket or restore from last working back up?

what are the major changes you did before getting this error - can you track the changes? looks to be some corruption with repository. is this error in your local environment?

you might need to work with Adobe Support to allow access for this domain.

Working in Localhost and Not working DEV instance - did you check the Network tab about the error details? Might be a Firewall or Dispatcher configuration required to pass/allow the outside domain request. Firewall or Network Restrictions: If it's working on your local machine but not on your DEV en...

please check this. https://medium.com/@toimrank/aem-and-elastic-search-integration-2f3db54cb86a

Digital Foundation Blue Print: Adobe Experience Manager (AEM) as a Cloud Service: Digital Foundation Blueprint is a reference implementation provided by Adobe. It's designed to help customers understand how to build, extend, and deploy sites on AEM as a Cloud Service. It includes examples of common ...

It is possible to add same tag to multiple assets or bulk assets. select assets in DAM folder and click on Properties and in Basic tab - you can select / add Tag  

Did you check the Audit log?   The Audit Log feature in AEM logs all the activities performed in the system, including changes to user and group permissions. To specifically log permission changes, you might need to create a custom event handler that listens for changes to the rep:policy nodes (whic...

is it downloading the dependencies ? try (force) mvn clean install  check your .m2 folder for the libraries (settings.xml)