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# ERR XReadGroup is cancelled

### Symptom

The client gets an exception similar to:

```
ReplyError: ERR XReadGroup is cancelled. Pending Entries List limit per consumer is about to be reached. Limit: 1000, Current PEL size: 90, Requested Read: 20, Key: mstream, Group: group1, Consumer: consumer1.
```

### Diagnosis

Pending Entries List of the stream for the consumer is full. For each consumer
in a consumer group, there is a pending entries list. This list keeps the
messages that are delivered to a consumer but not yet acknowledged via
[XACK](https://redis.io/commands/xack/). This list is populated via
[XREADGROUP](https://redis.io/commands/xreadgroup/).

### Solution

Acknowledge the consumed messages via [XACK](https://redis.io/commands/xack/)
from the list of the associated group and consumer.