How to fix ERR syntax error in Redis

Open the official Redis documentation for the command you're using. Check the exact argument order and format required.

# Example: SET command syntax
SET key value [EX seconds|PX milliseconds|EXAT unix-time-seconds|PXAT unix-time-milliseconds|KEEPTTL] [NX|XX] [GET]

Ensure your code matches this exact format.

Some commands and options are only available in newer Redis versions. Verify your server version supports the command and options you're using.

redis-cli
> INFO server

Look for the redis_version field and cross-reference with the command documentation to confirm compatibility.

Count the arguments you're passing and ensure they match Redis command requirements. For example, the INCR command takes exactly one argument (the key).

// Wrong: INCR with too many arguments
await client.incr('counter', 'extra'); // ERR syntax error

// Correct: INCR with one argument
await client.incr('counter');

When setting TTL, use proper syntax with EX (seconds) or PX (milliseconds) keywords.

// Wrong: third positional argument
await client.set('key', 'value', 3600); // ERR syntax error

// Correct: EX keyword with TTL
await client.set('key', 'value', { EX: 3600 });

// Also correct with node-redis v4+ syntax
await client.setEx('key', 3600, 'value');

Test your command in redis-cli to isolate the syntax issue from client code.

redis-cli
> SET mykey "myvalue" EX 3600
OK

If the command works in redis-cli but fails in your code, the issue is in how you're constructing the command in your client library.

If the issue persists, monitor the actual commands sent to Redis to see what's being transmitted.

redis-cli
> MONITOR

Then run your code and watch what commands appear. Compare them against Redis documentation to spot the syntax error. Be aware MONITOR reduces performance, so use it only for debugging.