What causes "HashImport ' ' has been discarded" in redis/jedis?

Create a new HashImport fieldset instance instead of reusing the discarded one

redis/jedis · error · IllegalStateException

HashImport ' ' has been discarded

Error message

HashImport '<name>' has been discarded

What it means

HashImportSupport.checkArgs validates a HashImport (a Redis hash-field import fieldset) before use. It throws IllegalStateException when the fieldset has already been discarded (e.g. after a failed prepare or explicit discard), since using it afterward would send stale or invalid state to the server. The name in the message identifies which fieldset was misused.

Solutions

Create a new HashImport fieldset instance instead of reusing the discarded one
Check fieldset.isDiscarded() before each import call and rebuild if true
Fix the root cause that led to the discard (usually a failed prepare/connection error) before retrying

Example fix

// before
HashImport fieldset = buildFieldset();
try {
  jedis.himport(namespace, key, fieldset, values);
} catch (JedisException e) {
  jedis.himport(namespace, key, fieldset, values); // IllegalStateException: discarded
}
// after
HashImport fieldset = buildFieldset();
try {
  jedis.himport(namespace, key, fieldset, values);
} catch (JedisException e) {
  HashImport fresh = buildFieldset();
  jedis.himport(namespace, key, fresh, values);
}

Defensive patterns

Strategy: validation

Validate before calling

if (fieldset == null || fieldset.isDiscarded()) {
  fieldset = rebuildFieldset();
}

Type guard

boolean usable(HashImport fs) { return fs != null && !fs.isDiscarded(); }

Try / catch

try {
  hashImportCall(fieldset, values);
} catch (IllegalStateException e) {
  if (e.getMessage().contains("discarded")) {
    fieldset = rebuildFieldset();
    hashImportCall(fieldset, values);
  } else throw e;
}

Prevention

Rebuild the fieldset for every import attempt instead of reusing instances
Check isDiscarded() before each use when fieldsets are long-lived
Wrap import retries in logic that constructs fresh fieldsets

When it happens

Trigger: Calling a hash-import command method with a HashImport fieldset after discard() was called on it, or after a failed prepare(Connection) left it discarded. checkArgs is invoked as the first step of every fieldset-consuming API call.

Common situations: Reusing a fieldset across two import calls where the first failed mid-way; catching an exception from a previous import and retrying with the same, now-discarded, HashImport object; long-lived fieldset objects held in application state that were discarded during a connection reset.

Understand the failure class

Background: "Invalid state transition" errors: "status must be X, actually Y", "already rejected/charging/uninstalled", "cannot ... while running" — what they mean when a library rejects your call — this error's family across 31 libraries.

Related errors

AI-assisted analysis of redis/jedis@6dac31d4c2 (2026-09-08). Data as JSON: /api/errors/5e9ec263d24ca871. Report an issue: GitHub.

Appendix: source

Thrown at src/main/java/redis/clients/jedis/HashImportSupport.java:19

package redis.clients.jedis;

/**
 * {@code HIMPORT SET} helpers: client-side argument validation, and the per-connection
 * prepare-before-use that a {@code himportSet} {@link CommandObject}'s
 * {@linkplain CommandObject#getPreProcessHooks() pre-process hook} runs. The hook is invoked by
 * {@link Connection#executeCommand(CommandObject)} once the {@code CommandExecutor} has picked a
 * connection &mdash; so retry / cluster redirection / failover stay in force &mdash; injecting a
 * {@code PREPARE} on that connection just before the {@code SET} when the fieldset is not yet
 * prepared there.
 */
final class HashImportSupport {

  private HashImportSupport() {
  }

  static void checkArgs(HashImport fieldset, int valueCount) {
    if (fieldset.isDiscarded()) {
      throw new IllegalStateException("HashImport '" + fieldset.name() + "' has been discarded");
    }
    if (valueCount != fieldset.size()) {
      throw new IllegalArgumentException("HashImport '" + fieldset.name() + "' expects "
          + fieldset.size() + " values but got " + valueCount);
    }
  }

  /**
   * Prepare-before-use: if {@code fieldset} is not yet prepared on {@code connection}, send
   * {@code HIMPORT PREPARE} and record it in the connection's note. The PREPARE is built here, only
   * when actually needed &mdash; the common already-prepared case allocates nothing. The caller
   * must own the connection.
   */
  static void prepareBeforeUse(Connection connection, HashImport fieldset) {
    if (!connection.himportState().isPrepared(fieldset.name())) {
      connection.executeCommand(new CommandArguments(Protocol.Command.HIMPORT)
          .add(Protocol.Keyword.PREPARE).add(fieldset.name()).addObjects(fieldset.fields()));
      markPrepared(connection, fieldset);

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