How to fix ERR Transaction was already aborted in Redis

When you see this error, the transaction is in a broken state. Clear it with DISCARD:

DISCARD

This resets the connection to normal state and clears all queued commands.

Review your MULTI/EXEC block for syntax errors:

MULTI
INCRBY mykey 1
SET mystring "value"
EXEC

Common issues:
- Wrong number of arguments (e.g., INCRBY missing argument)
- Unknown command name (typo)
- Invalid argument types
- WATCH conflict: another client modified the key

Before retrying, validate each command works in isolation:

INCRBY mykey 1
SET mystring "value"
GET mystring

Fix any failing commands before putting them in a MULTI block.

Look up the exact syntax for commands:

COMMAND INFO INCRBY
COMMAND INFO SET
COMMAND INFO LPUSH

This shows required vs optional arguments for each command.

WATCH conflicts should be handled gracefully:

let retries = 0;
while (retries < 3) {
  try {
    const result = await redis.watch('mykey');
    if (!result) {
      retries++;
      continue;
    }
    const multi = redis.multi();
    multi.set('mykey', newValue);
    const exec = await multi.exec();
    if (exec) break; // Success
    retries++;
  } catch (e) {
    retries++;
  }
}

With exponential backoff for better results in high-contention scenarios.

Check if server issues caused the abort:

INFO memory
INFO stats

If used_memory is near maxmemory or you see high CPU, the server may be under stress causing transaction failures.