KB484678: Community connector fails to connect to the Community Connectors server and results in an internal server error

Description 

Some of the Community Connectors, such as Elasticsearch, SurveyMonkey, etc., communicate to the data source server via the Community Connectors Web Server. 
For example, Elasticsearch sends requests to the Community Connector server to the

httpGetFill

endpoint with parameters set in the header: 
 

forward.Authorization : 'xxx',
forward.url: 'xxx'/

When you try to connect to an Elasticsearch server, the connection fails with the following error. 
HTTP/1.1 500 Internal Server Error: java.lang.NullPointerException 
 

Why is this happening? 

In many use cases, administrators may enable different security rules in their network. Some simple ones are Proxy, Nginx, etc., while some rules may block the HTTP requests with customized headers. 
Take Nginx for example; the

ignore_invalid_headers

setting is used to filter out invalid headers identified by Nginx, and by default, it's set to ON. This blocks the requests with headers mentioned above when they are sent to the Community Connectors server.

Solution 

For Nginx, in the

nginx.conf

file, set

ignore_invalid_headers

to OFF. For steps, refer to the Nginx documentation.
For other products, you must locate a similar setting to bypass the custom headers that are identified as invalid.