NOGROUP No such key or consumer group: No such key or consumer group in stream

What does it mean?

You ran a stream consumption command (XREADGROUP, XACK, XCLAIM, etc.), but the specified key (stream) or consumer group does not exist. The group/stream to operate on was not found.

Why does it happen?

The group was never created (XGROUP CREATE skipped); the stream key was deleted or never written; the group name/key is misspelled; or the group was removed with XGROUP DESTROY. Common when consumers start before the group is created.

How to fix it

First make sure the stream and group exist: XINFO STREAM stream and XINFO GROUPS stream. If the group is missing, create it: XGROUP CREATE stream group $ MKSTREAM (also creates the stream if needed). Add a step at application startup that creates the group (ignoring BUSYGROUP). Verify the key and group names are spelled correctly.