Join column not in input

A Join node's key names a column that one of its two inputs does not have. Without it no rows can be paired, so the run stops at the node, and the check before a run reports it too.

What to do

In the node's settings panel, choose a key column the named input has; the message lists its columns and suggests a close match where there is one. If the column should exist, check the earlier step that is meant to produce it.

Where it comes from

Shown by Join. It is one of the messages about a node.