without knowledge about your setup, help will not be possible. How did you install Graylog, what Version of Graylog did you have (is answered by the screenshot) but what Elasticsearch version did you have? How is that configured?
Welcome to Graylog and our friendly community! We hope you’ll enjoy both the software and the forums.
First rule of Fight Club… I mean… First rule of these forums is that you put in some effort into researching your problems. In this case, it would help both yourself and us a lot if you spent a few hours reading Graylog documentation.
Here’s a VERY basic overview of what you’re building here…
Graylog is the software that we use to both collect, process and query data from a lot of disparate sources.
Graylog uses a MongoDB backend for the storage of configuration settings.
Graylog uses an ElasticSearch backend for the storage of all processed data.
The Graylog OVA is a virtual machine that includes all three of these components, in a setup that is at best useful for a proof of concept environment. Performance will suck, stability may suck, etc.
MongoDB and ElasticSearch are NOT products of the Graylog project. They are open source database products that Graylog was built upon.
Properly running and managing MongoDB and ElasticSearch requires a skillset that includes Linux/Unix administration, but of course also basic knowledge of the two products.
In the case of your problem, it looks like the ElasticSearch database on your OVA got hosed. It could be as simple as rebooting the VM completely. It could also be a case of a full disk. Or who knows, maybe you accidentally broke a configuration file
The first error indicates that one input failed to start on one of your hosts. So that’s not altogether bad news. Question is: which input is it? I can’t tell from the numbers shown. Could it be that this particular input is told to run on a port <1024? Because that won’t work without extra trickery.
The other two messages indicate that Graylog is not able to push messages into ElasticSearch. Either ElasticSearch is refusing to accept your input, or Graylog cannot find ES. Since you are using the vendor-provided OVA, the latter is unlikely. Unless you went into the configuration and manually made changes.
When you go to System > Overview, what does the ElasticSearch status bar say? It -should- report that the Elastic status is “green”.
Unfortunately, the fact that earlier Graylog could not show you any indices suggests again that Graylog simply cannot talk to ElasticSearch. Either because ES is down, ES is broken, or because you manually made changes to the config file for Graylog.