What causes "COUNT or EXACTLY must be specified." in redis/jedis?

Call .count(n, order) or .exactly(n, order) on the LMoveMParams before executing the command

redis/jedis · error · IllegalArgumentException

COUNT or EXACTLY must be specified.

Error message

COUNT or EXACTLY must be specified.

What it means

LMPOP-style multi-list move params must carry a COUNT or EXACTLY selector before being serialized. LMoveMParams.addParams() throws this IllegalArgumentException when neither count(...) nor exactly(...) was called, because the command arguments would be incomplete/invalid.

Solutions

Call .count(n, order) or .exactly(n, order) on the LMoveMParams before executing the command
If you don't want a count, use the command overload that takes no LMoveMParams
Check factory/builder code paths to ensure one of the two selector methods is always invoked

Example fix

// before
LMoveMParams params = new LMoveMParams();
jedis.lmpop(keys, LeftRight.LEFT, params);
// after
LMoveMParams params = new LMoveMParams().count(3, ListMoveOrder.OBO);
jedis.lmpop(keys, LeftRight.LEFT, params);

Defensive patterns

Strategy: validation

Validate before calling

if (params == null || !hasSelector(params)) params = new LMoveMParams().count(n, ListMoveOrder.OBO);

Try / catch

try {
  jedis.lmpop(keys, LeftRight.LEFT, params);
} catch (IllegalArgumentException e) {
  jedis.lmpop(keys, LeftRight.LEFT, new LMoveMParams().count(1, ListMoveOrder.OBO));
}

Prevention

Always build LMoveMParams with count(...) or exactly(...) as the first call
Centralize params construction in one factory method
Don't pass bare new LMoveMParams() to the command

When it happens

Trigger: Executing the multi-list LMOVE/LMPOP command with LMoveMParams built only via builder methods other than count()/exactly() — e.g. an empty new LMoveMParams() or one constructed by a factory that only set the order.

Common situations: Building params conditionally where both count and exactly branches were skipped; reusing a params object whose selector was expected to be set elsewhere; misunderstanding that COUNT/EXACTLY is mandatory for this command form.

Understand the failure class

Background: "missing required argument" and "the following required arguments were not provided": what required-argument errors mean and how to fix them — this error's family across 20 libraries.

Related errors

AI-assisted analysis of redis/jedis@6dac31d4c2 (2026-09-08). Data as JSON: /api/errors/f8af903589d148dc. Report an issue: GitHub.

Appendix: source

Thrown at src/main/java/redis/clients/jedis/params/LMoveMParams.java:62

  /**
   * Move exactly {@code count} elements, or nothing (a {@code null} reply) if the source list does
   * not hold that many, ordered by {@code order}. Mutually exclusive with
   * {@link #count(int, ListMoveOrder)} (last call wins).
   */
  public LMoveMParams exactly(int count, ListMoveOrder order) {
    if (order == null) {
      throw new IllegalArgumentException("Ordering (OBO or BULK) must not be null.");
    }
    this.selector = Keyword.EXACTLY;
    this.count = count;
    this.order = order;
    return this;
  }

  @Override
  public void addParams(CommandArguments args) {
    if (selector == null || count == null) {
      throw new IllegalArgumentException("COUNT or EXACTLY must be specified.");
    }
    args.add(selector).add(count).add(order);
  }

  @Override
  public boolean equals(Object o) {
    if (this == o) return true;
    if (o == null || getClass() != o.getClass()) return false;
    LMoveMParams that = (LMoveMParams) o;
    return selector == that.selector && Objects.equals(count, that.count) && order == that.order;
  }

  @Override
  public int hashCode() {
    return Objects.hash(selector, count, order);
  }
}

View on GitHub (pinned to 6dac31d4c2)