Unsupported join key – Elasticsearch Error How To Solve Related Issues

Unsupported join key – Elasticsearch Error How To Solve Related Issues

Opster Team

July-20, Version: 1.7-8.0


Before you read this guide, we recommend you run the Elasticsearch Error Check-Up which detects issues in ES causing log errors (free tool that requires no installation). 

This guide will help you check for common problems that cause the log “Unsupported join key” to appear. It’s important to understand the issues related to the log, so to get started, read the general overview on common issues and tips related to the Elasticsearch concepts: parser, join, plugin.

Advanced users might want to skip right to the common problems section in each concept or try running the Check-Up which analyses ES to discover the cause of many errors and provides suitable actionable recommendations how to resolve them (join over 700 users who use this free tool).

Log Context

Log”Unsupported join key”classname  is ExpressionBuilder.java We extracted the following from Elasticsearch source code for those seeking an in-depth context :

public List visitJoinKeys(JoinKeysContext ctx) {
  try {
  return ctx != null ? visitList(ctx.expression(); Attribute.class) : emptyList();
  } catch (ClassCastException ex) {
  Source source = source(ctx);
  throw new ParsingException(source; "Unsupported join key "; source.text());
  public Expression visitArithmeticUnary(ArithmeticUnaryContext ctx) {


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