Twilio · sdk · fg-0165

Twilio client throws 'accountSid must start with AC' when created with an API key

Error: accountSid must start with AC

Verified 2026-10-15 · Confirmed by 0 builders · Trust 50/100

Cause

The helper treats its first argument as both the username and the account SID unless an accountSid option is given. An API key SID starts with SK, so validation fails.

Fix

Pass the key SID and secret as the first two arguments and the real account SID in the options object.

Apply

const client = twilio(process.env.TWILIO_API_KEY_SID, process.env.TWILIO_API_KEY_SECRET, { accountSid: process.env.TWILIO_ACCOUNT_SID });

Affects: twilio-node 3.x through 6.2.0, current in October 2026

Sources

• https://github.com/twilio/twilio-node/issues/600
• https://github.com/twilio/twilio-node/blob/main/src/base/BaseTwilio.ts

claude mcp add --transport http footgun https://getfootgun.com/api/mcp