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#2037·ioredis

`info` command issued after client enters subscriber mode

Author: nwalters512Created Oct 31, 2025Updated Sep 10, 2026
Labelsbug

I've noticed a new issue after upgrading from 5.8.0 to 5.8.2. I believe it's related to #2033.

Here's a self-contained reproduction:

typescript
import { Redis } from 'ioredis';

const sub = new Redis();

sub.psubscribe('socket.io#/#*');
sub.subscribe(['socket.io-request#/#', 'socket.io-response#/#', 'socket.io-response#/#3ywmsZ#']);

setTimeout(() => {
  sub.psubscribe('socket.io#/external-grading#*');
  sub.subscribe([
    'socket.io-request#/external-grading#',
    'socket.io-response#/external-grading#',
    'socket.io-response#/external-grading#TldK34#',
  ]);
}, 9);

The exact timeout will probably have to be tuned to a particular machine, but at least on mine, a 9ms timeout reproduces the following error quite reliably for me:

[ioredis] Unhandled error event: Error: Connection in subscriber mode, only subscriber commands may be used
    at EventEmitter.sendCommand (/Users/nathan/git/PrairieLearn/node_modules/ioredis/built/Redis.js:338:28)
    at EventEmitter.info (/Users/nathan/git/PrairieLearn/node_modules/ioredis/built/utils/Commander.js:90:25)
    at EventEmitter._readyCheck (/Users/nathan/git/PrairieLearn/node_modules/ioredis/built/Redis.js:655:14)
    at /Users/nathan/git/PrairieLearn/node_modules/ioredis/built/redis/event_handler.js:82:22
    at <anonymous>
node:internal/process/promises:394
    triggerUncaughtException(err, true /* fromPromise */);
    ^

Error: Connection in subscriber mode, only subscriber commands may be used
    at EventEmitter.sendCommand (/Users/nathan/git/PrairieLearn/node_modules/ioredis/built/Redis.js:338:28)
    at EventEmitter.info (/Users/nathan/git/PrairieLearn/node_modules/ioredis/built/utils/Commander.js:90:25)
    at EventEmitter._readyCheck (/Users/nathan/git/PrairieLearn/node_modules/ioredis/built/Redis.js:655:14)
    at /Users/nathan/git/PrairieLearn/node_modules/ioredis/built/redis/event_handler.js:82:22
    at <anonymous>

Node.js v24.6.0

I added logs here to try to see what the sequence of events was:

https://github.com/redis/ioredis/blob/105dc72ea7aa1c00b2bceba7f3698d89245b72d1/lib/utils/Commander.ts#L135

That yielded the following:

Trace: ioredis Commander socket.io#/#* psubscribe psubscribe
    at EventEmitter.psubscribe (/Users/nathan/git/PrairieLearn/node_modules/ioredis/built/utils/Commander.js:75:15)
    at file:///Users/nathan/git/PrairieLearn/apps/prairielearn/redis.mjs:5:5
    at ModuleJob.run (node:internal/modules/esm/module_job:371:25)
    at async onImport.tracePromise.__proto__ (node:internal/modules/esm/loader:669:26)
    at async asyncRunEntryPointWithESMLoader (node:internal/modules/run_main:101:5)
Trace: ioredis Commander [
  'socket.io-request#/#',
  'socket.io-response#/#',
  'socket.io-response#/#3ywmsZ#'
] subscribe subscribe
    at EventEmitter.subscribe (/Users/nathan/git/PrairieLearn/node_modules/ioredis/built/utils/Commander.js:75:15)
    at file:///Users/nathan/git/PrairieLearn/apps/prairielearn/redis.mjs:6:5
    at ModuleJob.run (node:internal/modules/esm/module_job:371:25)
    at async onImport.tracePromise.__proto__ (node:internal/modules/esm/loader:669:26)
    at async asyncRunEntryPointWithESMLoader (node:internal/modules/run_main:101:5)
Trace: ioredis Commander SETINFO LIB-NAME ioredis client client
    at EventEmitter.client (/Users/nathan/git/PrairieLearn/node_modules/ioredis/built/utils/Commander.js:75:15)
    at Socket.<anonymous> (/Users/nathan/git/PrairieLearn/node_modules/ioredis/built/redis/event_handler.js:70:18)
    at Object.onceWrapper (node:events:622:28)
    at Socket.emit (node:events:520:35)
    at afterConnect (node:net:1622:10)
    at afterConnectMultiple (node:net:1729:3)
Trace: ioredis Commander SETINFO LIB-VER 5.8.2 client client
    at EventEmitter.client (/Users/nathan/git/PrairieLearn/node_modules/ioredis/built/utils/Commander.js:75:15)
    at /Users/nathan/git/PrairieLearn/node_modules/ioredis/built/redis/event_handler.js:65:22
    at async Promise.all (index 0)
Trace: ioredis Commander socket.io#/external-grading#* psubscribe psubscribe
    at EventEmitter.psubscribe (/Users/nathan/git/PrairieLearn/node_modules/ioredis/built/utils/Commander.js:75:15)
    at Timeout._onTimeout (file:///Users/nathan/git/PrairieLearn/apps/prairielearn/redis.mjs:9:7)
    at listOnTimeout (node:internal/timers:608:17)
    at process.processTimers (node:internal/timers:543:7)
Trace: ioredis Commander [
  'socket.io-request#/external-grading#',
  'socket.io-response#/external-grading#',
  'socket.io-response#/external-grading#TldK34#'
] subscribe subscribe
    at EventEmitter.subscribe (/Users/nathan/git/PrairieLearn/node_modules/ioredis/built/utils/Commander.js:75:15)
    at Timeout._onTimeout (file:///Users/nathan/git/PrairieLearn/apps/prairielearn/redis.mjs:10:7)
    at listOnTimeout (node:internal/timers:608:17)
    at process.processTimers (node:internal/timers:543:7)
Trace: ioredis Commander [Function (anonymous)] info info
    at EventEmitter.info (/Users/nathan/git/PrairieLearn/node_modules/ioredis/built/utils/Commander.js:75:15)
    at EventEmitter._readyCheck (/Users/nathan/git/PrairieLearn/node_modules/ioredis/built/Redis.js:656:14)
    at /Users/nathan/git/PrairieLearn/node_modules/ioredis/built/redis/event_handler.js:82:22
    at <anonymous>
    at process.processTicksAndRejections (node:internal/process/task_queues:105:5)
Trace: bad command info
    at EventEmitter.sendCommand (/Users/nathan/git/PrairieLearn/node_modules/ioredis/built/Redis.js:338:23)
    at EventEmitter.info (/Users/nathan/git/PrairieLearn/node_modules/ioredis/built/utils/Commander.js:91:25)
    at EventEmitter._readyCheck (/Users/nathan/git/PrairieLearn/node_modules/ioredis/built/Redis.js:656:14)
    at /Users/nathan/git/PrairieLearn/node_modules/ioredis/built/redis/event_handler.js:82:22
    at <anonymous>
    at process.processTicksAndRejections (node:internal/process/task_queues:105:5)
[ioredis] Unhandled error event: Error: Connection in subscriber mode, only subscriber commands may be used
    at EventEmitter.sendCommand (/Users/nathan/git/PrairieLearn/node_modules/ioredis/built/Redis.js:339:28)
    at EventEmitter.info (/Users/nathan/git/PrairieLearn/node_modules/ioredis/built/utils/Commander.js:91:25)
    at EventEmitter._readyCheck (/Users/nathan/git/PrairieLearn/node_modules/ioredis/built/Redis.js:656:14)
    at /Users/nathan/git/PrairieLearn/node_modules/ioredis/built/redis/event_handler.js:82:22
    at <anonymous>
    at process.processTicksAndRejections (node:internal/process/task_queues:105:5)
node:internal/process/promises:394
    triggerUncaughtException(err, true /* fromPromise */);
    ^

Error: Connection in subscriber mode, only subscriber commands may be used
    at EventEmitter.sendCommand (/Users/nathan/git/PrairieLearn/node_modules/ioredis/built/Redis.js:339:28)
    at EventEmitter.info (/Users/nathan/git/PrairieLearn/node_modules/ioredis/built/utils/Commander.js:91:25)
    at EventEmitter._readyCheck (/Users/nathan/git/PrairieLearn/node_modules/ioredis/built/Redis.js:656:14)
    at /Users/nathan/git/PrairieLearn/node_modules/ioredis/built/redis/event_handler.js:82:22
    at <anonymous>
    at process.processTicksAndRejections (node:internal/process/task_queues:105:5)

It seems like it tries to issue info commands after the client has already entered subscriber mode.

Source: redis/ioredis

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