Could not parse http response expected a header value for header – How to solve this Elasticsearch exception

Opster Team

August-23, Version: 6.8-7.15

Briefly, this error occurs when Elasticsearch is unable to parse the HTTP response due to a missing or malformed header value. This could be due to a misconfiguration in the request or a problem with the server’s response. To resolve this issue, you can: 1) Check the syntax of your HTTP request to ensure all headers are correctly formatted and included. 2) Verify the server’s response to ensure it’s returning the expected headers. 3) Update or reinstall Elasticsearch to the latest version to fix any potential bugs.

This guide will help you check for common problems that cause the log ” could not parse http response. expected a header value for header ” to appear. To understand the issues related to this log, read the explanation below about the following Elasticsearch concepts: plugin, response.

Log Context

Log “could not parse http response. expected a header value for header” class name is We extracted the following from Elasticsearch source code for those seeking an in-depth context :

 headers.put(headerName; new String[] { String.valueOf(parser.objectText()) });
 } else if (token == XContentParser.Token.START_ARRAY) {
 List values = new ArrayList<>();
 while ((token = parser.nextToken()) != XContentParser.Token.END_ARRAY) {
 if (token.isValue() == false) {
 throw new ElasticsearchParseException("could not parse http response. expected a header value for header " +
 "[{}] but found [{}] instead"; headerName; token);
 } else {