Also, when I was submitting this post I received another error.
and also I m unable to upload any pdf or zip file on my forum.... which is why I came here to find a solution..
That error will only show if ElasticSearch is offline (or not responding). Probably means new content isn't being indexed while it's been offline either (for when it comes back online).
Time to be using multiple nodes imo... it's what ES is good at.
Is there any reason people don't use monit with elasticsearch? poll for elastic search status every minute and start/restart it if it is not responding imho sounds like something that can avoid longer periods of search unavailability.
I was hoping we'd be notified what the trouble was.
Might help to know what the issue was for other admins who could run into that problem.
Sharing your experience helps others.