How to fix ERR The $ ID is meaningless in the context of XREADGROUP in Redis

RedisINTERMEDIATEMEDIUM

This error occurs when attempting to use the special $ ID with the XREADGROUP command. While $ represents the last entry in a stream, it cannot be used with XREADGROUP because consumer groups have different semantics for reading messages.

What this error means

This error message appears when you try to use the special stream ID `$` with the XREADGROUP command in Redis Streams. The `$` ID represents "the last entry in the stream" and works perfectly with the XREAD command, but it has no meaningful interpretation in the context of consumer groups. XREADGROUP is designed to read messages from a consumer group, which maintains its own state of which messages have been delivered to consumers. When reading from a consumer group, you either want to read pending messages (by specifying an actual message ID) or fetch new messages that haven't been delivered to any consumer yet (by using the special `>` ID). The `$` ID doesn't fit either of these use cases. This error often confuses developers because Redis may suggest using `$` in error messages related to stream IDs, but that suggestion is contextual to XREAD, not XREADGROUP. Understanding the distinction between stream reading modes and consumer group semantics is key to avoiding this error.

How to fix "ERR The $ ID is meaningless in the context of XREADGROUP"

1Use > to read new messages from consumer group

Replace the $ ID with > to fetch only new messages that haven't been delivered to any consumer in the group:

bash

# Incorrect - causes the error
XREADGROUP GROUP mygroup consumer1 STREAMS mystream $

# Correct - reads new messages only
XREADGROUP GROUP mygroup consumer1 STREAMS mystream >

javascript

// Node.js with node-redis
const messages = await client.xReadGroup(
  'mygroup',
  'consumer1',
  { key: 'mystream', id: '>' },  // Use > not $
  { COUNT: 10, BLOCK: 5000 }
);

The > special ID tells Redis to return only messages never delivered to other consumers so far, which is typically what you want when consuming from a group.

2Specify an actual message ID to read pending messages

If you want to read the history of pending messages for this consumer, use a specific message ID or 0-0 to read from the beginning:

bash

# Read pending messages from the beginning
XREADGROUP GROUP mygroup consumer1 STREAMS mystream 0-0

# Read pending messages from a specific ID
XREADGROUP GROUP mygroup consumer1 STREAMS mystream 1234567890123-0

python

# Python with redis-py
messages = r.xreadgroup(
    groupname='mygroup',
    consumername='consumer1',
    streams={'mystream': '0-0'},  # Read from beginning
    count=10
)

This retrieves messages that were previously delivered to this consumer but not yet acknowledged with XACK.

3Understand the difference between XREAD and XREADGROUP IDs

Remember that $ is valid for XREAD but not XREADGROUP:

XREAD with $:

bash

# Valid - $ means "from the end of stream"
XREAD STREAMS mystream $

XREADGROUP with >:

bash

# Valid - > means "new messages not yet delivered"
XREADGROUP GROUP mygroup consumer1 STREAMS mystream >

When creating a consumer group, you CAN use $ to set the starting position:

bash

# Valid - consumer group starts from end of stream
XGROUP CREATE mystream mygroup $ MKSTREAM

The key distinction: $ sets a position during group creation, but > is used when reading from an existing group.

4Verify consumer group exists before reading

Ensure your consumer group is properly created before attempting to read:

bash

# Create the consumer group first
XGROUP CREATE mystream mygroup 0 MKSTREAM

# Then read with >
XREADGROUP GROUP mygroup consumer1 STREAMS mystream >

javascript

// Node.js - create group with error handling
try {
  await client.xGroupCreate('mystream', 'mygroup', '0', {
    MKSTREAM: true
  });
} catch (err) {
  if (!err.message.includes('BUSYGROUP')) {
    throw err;
  }
  // Group already exists, continue
}

// Now read with >
const messages = await client.xReadGroup(
  'mygroup',
  'consumer1',
  { key: 'mystream', id: '>' },
  { COUNT: 10 }
);

How to fix ERR The $ ID is meaningless in the context of XREADGROUP in Redis

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How to fix "ERR The $ ID is meaningless in the context of XREADGROUP"

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